Marinate: In a bowl, whisk egg, buttermilk, salt, pepper, garlic powder, and onion powder. Add chicken; toss and let rest 10–15 minutes.
Prep Coating: In another bowl, combine flour, cornstarch, and baking powder.
Dredge: Drain chicken from marinade (reserve liquid). Coat in dry mix, shaking off excess. For extra crisp, dip back in marinade and re‑coat.
Heat Oil: Warm oil to 350 °F (175 °C) in a deep skillet or Dutch oven.
Fry: Fry chicken in small batches for 3–4 minutes until golden and 165 °F inside. Transfer to a wire rack to drain.
Make Sauce: Whisk together mayonnaise, sweet chili sauce, Sriracha, honey, rice vinegar, sesame oil, and salt. Chill 5–10 minutes.
Assemble: Arrange chicken on a platter. Drizzle or gently toss with sauce. Garnish and serve immediately.