Rinse and (optionally) soak: Place the rice in a fine-mesh strainer and rinse under cold water until the water runs clear. If using basmati, soak for 15–30 minutes then drain.
Prep aromatics: Finely dice the onion, mince the garlic, and dice the carrots (if using). Warm the stock in a small saucepan or microwave. If using saffron, bloom the threads in 2 tablespoons of warm stock and set aside.
Toast nuts (if using): In a dry skillet over medium heat, toast slivered almonds or pine nuts until fragrant and golden (30–90 seconds). Remove and set aside.
Heat fat: In a heavy-bottomed saucepan over medium heat, add the oil and 1 tablespoon butter. Swirl to coat.
Sauté aromatics: Add the diced onion (and carrots if using) with a pinch of salt. Cook, stirring occasionally, until the onion is soft and translucent, about 4–6 minutes. Add the garlic and cook 30–45 seconds until fragrant.
Toast the rice: Add the drained rice to the pan and stir to coat every grain in the fat and aromatics. Toast the rice for 2–4 minutes, stirring frequently, until it smells nutty and the edges turn slightly translucent. If adding whole spices (cumin seeds), add them now to bloom.
Deglaze (optional): Splash in 2 tablespoons dry white wine if using and let it reduce almost completely — this adds depth.
Add stock and season: Pour in the warm stock (and saffron + its soaking liquid if using). Add the bay leaf, 1/2 tsp kosher salt (adjust if stock is salty), and a few grinds of black pepper. Bring to a gentle simmer.
Cover and cook: Reduce heat to low, cover tightly, and simmer undisturbed for 15–18 minutes for long-grain white rice (start checking at 15 minutes). Do not lift the lid repeatedly.
Rest and finish: Remove from heat and keep covered for 10 minutes to let steam finish the rice. Remove the bay leaf. Add the remaining 1 tablespoon butter, gently fold in toasted nuts (if using), lemon zest, and chopped herbs. Fluff with a fork to separate the grains.
Serve: Transfer to a warmed serving dish and garnish with additional herbs or nuts as desired.