Keto Garlic Butter Beef Tenderloin
If you want an impressive, restaurant-quality main that’s entirely low-carb and blissfully simple, this Keto Garlic Butter Beef Tenderloin is the recipe to turn to. Tenderloin is the most tender cut of beef, and when you finish it with a rich garlic-herb butter and a perfect sear, you get melt-in-your-mouth slices that feel indulgent without wrecking a keto day. I’ll walk you through every detail — ingredients, technique, timing, equipment, variations, plating, pairings, storage, and troubleshooting — so you’ll get flawless results every time.
Why this recipe works (and why tenderloin is a great keto choice)
Beef tenderloin is naturally lean compared with ribeye or strip steak, but pairing it with a rich garlic butter brings back the mouthfeel and satiation keto eaters crave — fat without carbs. This recipe focuses on:
- Texture: gentle roasting + a hot sear (or reverse sear) gives an even medium-rare from edge to edge.
- Fat balance: compound garlic butter adds flavor and healthy satiety for a keto plate.
- Simplicity: minimal ingredients with maximum impact — fresh aromatics and precise technique.
- Versatility: works whole, as medallions, or sous-vide for perfect control.
Use this guide to get a tender, evenly cooked center, a flavorful crust, and buttery finish that melts over each slice.
Ingredients (serves 4–6)
Percentages and substitutions are given so you can scale.
For the beef
- 2–3 lb (900 g–1.4 kg) beef tenderloin, trimmed and tied (center-cut whole roast). If using individual steaks/medallions: choose 1–1.5-inch thick pieces.
- Kosher salt — generous (see seasoning section).
- Freshly ground black pepper.
For the keto garlic butter (compound butter)
- 8 tablespoons (1 stick / 113 g) unsalted butter, softened to room temperature.
- 3–4 garlic cloves, finely grated or minced (about 2 tablespoons).
- 1 tablespoon fresh parsley, finely chopped.
- 1 teaspoon fresh thyme leaves, chopped (or ½ tsp dried thyme).
- 1 teaspoon lemon zest (optional — a little brightens, but adds negligible carbs).
- Sea salt and freshly ground black pepper to taste.
Optional finishing & basting
- 1–2 tablespoons olive oil or avocado oil (for searing).
- 2 tablespoons unsalted butter (for pan basting).
- 2–3 sprigs fresh rosemary or thyme and 2 garlic cloves smashed (for basting aroma).
Keto-friendly serving suggestions
- Cauliflower mash, roasted asparagus, garlic sautéed spinach, buttered mushrooms, or a crisp green salad with high-fat dressing.
Equipment you’ll want
- Oven with reliable thermostat.
- Heavy skillet (preferably cast iron) for searing.
- Instant-read thermometer (essential).
- Roasting rack and sheet pan (for whole tenderloin).
- Kitchen twine (if your tenderloin isn’t already tied).
- Small bowl and spoon for compound butter.
- Cutting board and sharp carving knife.
Prep work: trimming, tying, and seasoning
Trimming & tying
A true professional finish starts with even shape. Trim excess silver skin and loose fat with a sharp knife. If the tenderloin tapers at one end, you can fold and tie it so the roast is uniform thickness — this ensures even cooking.
Tie the roast loosely at 1–1.5 inch intervals with kitchen twine. If you’re using medallions, no tying required.
Seasoning
- Pat the beef dry with paper towels to promote browning.
- Season generously with kosher salt and a light dusting of black pepper. For a 2–3 lb tenderloin, use roughly 1.5–2 teaspoons kosher salt (adjust to taste). Salt early: 30–60 minutes before cooking if possible (dry brine) for better flavor and texture.
- Let the roast sit at room temperature for 30–60 minutes before roasting if your kitchen is cool; this helps with even doneness.
Make the garlic butter (compound butter)
- In a small bowl, combine softened butter, grated garlic, chopped parsley, thyme, lemon zest (if using), and a pinch of salt and pepper.
- Mash together with a fork until completely homogenized. Taste and adjust salt/garlic.
- For convenience, you can roll the compound butter in plastic wrap into a log and chill. Slice discs to top the meat after roasting, or use softened butter right away for basting.
This garlic butter is the flavor engine for the recipe — it carries the garlic and herbs deep into the meat and melts into the carved slices.
Cooking methods — choose one (all yield excellent Keto Garlic Butter Beef Tenderloin)
I outline three reliable approaches: reverse sear (recommended for large roasts), classic sear-then-roast, and sous-vide. Each method includes exact temps and timings; always rely on an instant-read thermometer for doneness.
Method A — Reverse sear (best for even medium-rare, recommended)
Reverse sear gives superb edge-to-edge doneness and a short final sear for a glorious crust.
- Preheat oven to 225°F (107°C).
- Place tenderloin on a rack set in a rimmed sheet pan. Insert thermometer probe into the thickest part.
- Roast until internal temperature reaches 115–120°F (46–49°C) for a final target of 125–130°F for medium-rare. For a 2–3 lb roast, this typically takes 35–60 minutes, but depend on size — temperature, not time, is your guide.
- Remove roast, tent loosely with foil and rest 10 minutes while you heat a heavy skillet (cast iron) over high heat with 1–2 tbsp oil until just smoking.
- Add roast and sear all sides quickly (30–60 seconds per side) to develop a deep crust. During the last 20–30 seconds, add 2 tbsp butter, smashed garlic and herbs; tilt pan and spoon butter over the roast (baste).
- Transfer to cutting board, top with slices of garlic butter, and let rest 8–10 minutes before slicing. Final temp should rise to 125–130°F (52–54°C) for medium-rare.
Method B — Sear then roast (classic, faster)
- Preheat oven to 425°F (220°C).
- Heat cast iron pan over high heat with oil. Sear the tenderloin on all sides until deeply browned (about 2 minutes per side), including ends.
- Move pan to oven or transfer roast to rack in roasting pan. Roast until internal temp 125–130°F (52–54°C) for medium-rare — roughly 12–18 minutes for smaller roasts; again, depend on size and thickness.
- Remove, baste with garlic butter, tent and rest 8–10 minutes.
Method C — Sous-vide (precision cook, perfect for medallions)
- Season roast or medallions and vacuum-seal with a tablespoon of olive oil or a bit of butter.
- Set sous-vide to 129°F (54°C) for medium-rare, and cook 1.5–3 hours (depending on thickness).
- Remove, pat dry, sear in a screaming-hot pan 30–60 seconds per side with a dab of oil; finish with garlic butter and rest briefly.
How to tell doneness (thermometer guide — do not guess)
Always use an instant-read thermometer and insert it into the center:
- Rare: 120–125°F (49–52°C)
- Medium-rare: 125–130°F (52–54°C) — the sweet spot for tenderloin.
- Medium: 135–140°F (57–60°C)
- Medium-well: 145–150°F (63–66°C)
Remember: carryover cooking raises internal temperature by ~5–10°F while resting. Aim a few degrees below your target when removing from heat.
Searing & basting technique (for glossy, flavor-packed crust)
- Use a heavy pan (cast iron) and heat until very hot. Add high-smoke oil (avocado or grapeseed).
- Sear evenly — don’t move the roast too early. A deep brown crust equals flavor.
- Add butter, smashed garlic, and herb sprigs in the last 30–45 seconds. Tilt the pan and spoon the butter over the roast — this adds flavor and helps develop a shiny glaze.
- Once seared, rest. Top with compound garlic butter so it melts into the meat.
Resting and carving: don’t skip it
Resting is crucial. Tent the meat loosely with foil and let it rest for 8–12 minutes for a small roast (longer for larger). Resting:
- Redistributes juices so they don’t run out on the cutting board.
- Allows the temperature to stabilize.
- Lets the garlic butter melt and set flavors.
When carving, remove twine, slice into ½-inch to 1-inch slices (or thicker if you prefer). Slice against the grain for maximum tenderness.
Serving suggestions — keto plates that elevate the dish
Keto Garlic Butter Beef Tenderloin is luxurious on its own — keep sides simple and fatty to balance macros.
- Creamy cauliflower mash with roasted garlic and parmesan.
- Browned butter sautéed asparagus with lemon zest.
- Garlic-buttered mushrooms (shiitake or cremini) finished with a splash of heavy cream (optional).
- Pan-seared Brussels sprouts with crispy pancetta (or bacon) — great texture contrast.
- Spinach gratin made with cream cheese and cheddar (low carb).
- Simple green salad with avocado, toasted walnuts, and a lemon-olive oil vinaigrette.
Garnish with fresh parsley and a small pat of compound garlic butter on top of the sliced beef — visually striking and decadent.
Beverage pairings (keto-friendly)
- Red wine: a glass of Cabernet Sauvignon, Malbec, or Syrah pairs beautifully with beef. If you track carbs, stick to a 5–6 oz pour — generally 3–4 g carbs per glass depending on wine.
- Sparkling water with lemon for a zero-carb option.
- Dry sparkling wine (brut) — lower residual sugar.
- Full-bodied, unsweetened iced tea or coffee for a non-alcoholic choice.
Variations & flavor riffs
- Bacon-wrapped tenderloin: wrap with thin bacon strips and secure with toothpicks. Sear bacon side first and roast until bacon is crisp and internal temp as desired.
- Herb crust: mix almond flour (keto binder), minced garlic, Dijon, chopped rosemary and parsley; press onto roast before searing for a crunchy, herby exterior.
- Blue cheese garlic butter: fold 2 oz blue cheese into the compound butter for a tangy finish.
- Truffle garlic butter: add ½–1 teaspoon truffle oil or ½ teaspoon truffle salt for a luxurious aroma.
- Spicy garlic butter: add ½ teaspoon smoked paprika and a pinch of cayenne for warmth.
Nutrition estimates (approximate, per serving)
Nutrition will vary by exact weight and portion size. For a 6 oz (170 g) cooked serving of tenderloin topped with about 1 tablespoon garlic butter, estimate:
- Calories: ~450–550 kcal
- Fat: 35–45 g (butter + beef)
- Protein: 35–40 g
- Carbs: 1–3 g (mostly from herbs/garlic; negligible for keto)
- Fiber: 0–1 g
These are estimates — if you need precise macros for strict tracking, weigh your portions and use a nutrition calculator with your ingredient specifics.
Make-ahead, storage & reheating
Make-ahead
- Compound garlic butter can be made up to 5 days refrigerated or frozen for longer storage.
- You can roast the tenderloin, slice, and chill for up to 2 days, then reheat gently before serving (see reheating).
Refrigeration & freezing
- Store leftover cooked beef in an airtight container in the refrigerator for 3–4 days.
- Freeze slices or whole roast (vacuum sealed or tightly wrapped) for up to 3 months.
Reheating (keep it tender)
- Reheat gently in a low oven: place slices on a baking sheet, cover loosely with foil, and warm at 250°F (120°C) until center reaches 110–120°F.
- Alternatively, reheat sous-vide style in a 120°F bath for 30–45 minutes for very gentle warming.
- Finish with a quick sear in a hot pan (30 seconds per side) and a fresh drizzle of compound butter.
Avoid microwaving if possible — it dries lean meat.
Troubleshooting — common mishaps & fixes
- Overcooked interior: If you overshoot temp, slice and serve thinly with a rich sauce (garlic butter or mushroom cream) and focus on moistening the meat.
- Pale crust/no sear: Pat meat dry and make sure pan is screaming hot. Don’t crowd pan.
- Underseasoned: Season early; use compound butter to punch flavor. Serve with a seasoned pan sauce if needed (deglaze with beef stock and reduce, then whisk in butter).
- Garlic too sharp: If raw garlic in compound butter tastes harsh, gently cook the garlic in butter for a minute before mixing (smells sweeter), or reduce raw garlic and add roasted garlic instead.
Advanced tips from a pro chef
- Dry brine: Salt the roast 1–24 hours before cooking and refrigerate uncovered. This concentrates flavor and helps with crust formation.
- Room temperature: Let chilled roast sit 30–60 minutes before cooking to reduce temperature differential and even cooking.
- Use a probe thermometer: For stress-free cooking, set a leave-in probe to alarm at your final target temp minus 3–5°F for resting.
- Finish with acid: A tiny squeeze of lemon or a splash of sherry vinegar on the plate brightens the rich garlic butter.
- Searing surface: Use a cast iron or stainless steel pan — they retain heat and create Maillard reaction (the brown crust).
- Fat layering: If using lean tenderloin, sear with oil first, then baste with butter at the end so butter doesn’t burn.
A chef’s suggested timeline (dinner party for 4)
- 3 hours ahead: Make compound garlic butter and refrigerate. If dry brining, salt the roast and refrigerate uncovered.
- 60 minutes ahead: Remove roast from fridge, tie (if needed), let come toward room temp.
- 30–15 minutes ahead: Preheat oven (use reverse sear or sear-then-roast method depending on choice). Prepare sides.
- 0–60 minutes: Cook roast (timing depends on method). Use thermometer, sear and baste.
- After roasting: Rest 8–12 minutes, slice, plate and top with melted garlic butter. Serve immediately.
Frequently Asked Questions
Q: Is tenderloin the best cut for a keto diet?
A: It’s excellent for tenderness and protein, but because it’s lean you’ll want to add butter, pan sauce, or fatty sides to hit keto fat goals.
Q: Can I use grass-fed beef?
A: Absolutely — it adds flavor complexity. Cooking times are the same, but flavor differs slightly.
Q: How do I scale to more guests?
A: Aim for 6–8 oz cooked beef per person for a generous serving. For parties, consider multiple smaller tenderloins or medallions.
Q: Can I use frozen tenderloin?
A: Thaw completely in the refrigerator before cooking. Sous-vide can accommodate from frozen, but oven methods should use thawed meat.
Final presentation & plating tips
- Slice on a warm cutting board to maintain juices — wipe the board between slices for tidy presentation.
- Fan slices slightly and place a small quenelle (or pat) of garlic butter on top so it melts into the meat.
- Add bright green vegetable (asparagus or microgreens) for color contrast and texture.
- Use a warm platter — cold plates chill the meat too quickly.
Closing — make it yours
This Keto Garlic Butter Beef Tenderloin is a showstopping centerpiece: elegant, richly flavored, and tailored for low-carb living. Follow the steps above, choose the cooking method that fits your rhythm (I personally favor the reverse sear for consistent medium-rare), and don’t skimp on the compound garlic butter — that’s the finishing touch that makes every bite sing.
Keto Garlic Butter Beef Tenderloin
Ingredients
- 2½ lb 1.13 kg beef tenderloin, trimmed and tied (center-cut whole roast)
- Kosher salt and freshly ground black pepper
- 1 –2 tbsp avocado oil or olive oil for searing
- Garlic Butter compound butter
- 8 tablespoons 113 g unsalted butter, softened
- 3 –4 garlic cloves finely grated or minced (about 2 tbsp)
- 1 tbsp fresh parsley finely chopped
- 1 tsp fresh thyme leaves chopped (or ½ tsp dried thyme)
- 1 tsp lemon zest optional
- Sea salt and freshly ground black pepper to taste
- Optional for basting
- 2 tbsp unsalted butter
- 2 garlic cloves smashed
- 2 –3 sprigs fresh rosemary or thyme
Instructions
- Trim & tie (if necessary). Trim any silver skin and excess fat. If the tenderloin tapers, fold the thin end under and tie the roast at 1–1.5″ intervals so it cooks evenly.
- Make the garlic butter. In a small bowl, combine the softened butter, grated garlic, chopped parsley, thyme, lemon zest (if using), and a pinch of salt and pepper. Mix until smooth. You may form into a log and chill or leave soft for immediate use.
- Dry brine & rest. Pat the roast dry. Generously season all over with kosher salt and a light grind of black pepper. For best flavor and texture, salt the roast 30–60 minutes before cooking or up to 24 hours in advance (refrigerate uncovered if doing long dry brine). Remove from fridge ~30–45 minutes before cooking to come toward room temperature.
- Choose your cooking method. (Reverse sear recommended for even medium-rare.)
- Reverse sear (recommended): Preheat oven to 225°F (107°C). Place roast on a rack set in a rimmed sheet pan. Roast until internal temperature reaches 115–120°F (46–49°C) for a final target of 125–130°F (52–54°C) medium-rare (about 35–60 minutes depending on size). Remove and tent.
- Sear-then-roast (classic): Preheat oven to 425°F (220°C). Heat a heavy skillet until very hot. Sear roast in oil 2 minutes per side to brown. Transfer to oven and roast until internal temp is 125–130°F (52–54°C) (typically 12–18 minutes; check with thermometer).
- Sous-vide (precision): Season and vacuum-seal roast; cook at 129°F (54°C) for 1.5–3 hours, then pat dry and sear 30–60 seconds per side.
- Sear & baste (finish). If reverse searing: heat a heavy skillet (cast iron) over high heat with 1–2 tbsp oil until just smoking. Sear roast quickly on all sides to form a crust (30–60 seconds per side). In the last 20–45 seconds, add 2 tbsp butter, smashed garlic and herb sprigs to the pan and spoon the foaming butter over the roast (baste) for flavor and sheen.
- Top with garlic butter & rest. Transfer roast to a cutting board, top with slices or a pat of the compound garlic butter so it begins to melt. Tent loosely with foil and rest 8–12 minutes (resting allows juices to redistribute and carryover heat to reach final doneness).
- Carve & serve. Remove twine. Slice roast into ½–1″ slices against the grain. Arrange on a warm platter, spoon any pan juices and melted garlic butter over the slices, and garnish with a sprinkle of chopped parsley and a twig of thyme or rosemary.
Notes
- Don’t skip the thermometer. Internal temperature is the most reliable guide: 125–130°F (52–54°C) for medium-rare. Aim a few degrees below your target when removing from heat to allow for carryover.
- Dry brine for better crust and deeper flavor. Salt the roast 1–24 hours before cooking and refrigerate uncovered if possible.
- Make-ahead: Compound garlic butter can be made up to 5 days ahead (refrigerated) or frozen for longer. The butter also makes a great finishing touch on other steaks or roasted vegetables.
- Storage: Refrigerate leftovers in an airtight container up to 3–4 days. Freeze (vacuum-sealed or tightly wrapped) up to 3 months.
- Reheating: Warm gently in a 250°F oven until just warmed through (avoid high heat that dries the meat). A short sear after warming refreshes the crust.
- Variations: Wrap with bacon for added fat, mix blue cheese into the compound butter, or press an almond-flour herb crust on before searing for texture.
- Keto tip: Serve with buttery cauliflower mash, sautéed mushrooms, or roasted asparagus to keep the plate low-carb and satisfying.