Pat wings dry very well with paper towels. Drier skin means crispier results.
Toss wings with salt, white pepper, black pepper, garlic powder, onion powder, and baking powder. Spread on a rack over a sheet pan.
Refrigerate uncovered 30–90 minutes. The skin dries out and the meat absorbs seasoning.
Combine cornstarch and rice flour in a shallow bowl. Stir to blend evenly.
Right before frying, dredge wings lightly in the starch mixture. Shake off excess. Coat every surface but avoid thick clumps.
Heat oil to 325°F (163°C) in a deep, heavy pot. Use a thermometer for accuracy.
Fry wings in batches without crowding, 7–9 minutes until lightly golden and cooked through. Maintain 300–325°F.
Transfer to a rack to drain. Rest 5 minutes. This rest helps the crust set.
Increase oil to 375°F (190°C). Fry wings again in batches for 1.5–2.5 minutes until deep golden and ultra-crisp.
Drain on a rack. The double fry keeps the crust crunchy for longer.
In a large wok or skillet over medium heat, add 1 tbsp oil. Add garlic and scallion whites; cook 20–30 seconds until fragrant.
Add sliced chilies and stir 15 seconds. Sprinkle in white pepper and optional Sichuan pepper. Turn off heat.
Add hot wings to the pan, toss to coat, then season with flaky salt to taste. Finish with scallion greens. Squeeze lime at the table.
