Break down chicken (optional): If starting with a whole chicken, you’ll need to break it down into bone-in pieces. Using a sharp knife, divide chicken into drumsticks, thighs, wings, and split breasts.

Marinate chicken: In a large bowl, whisk together buttermilk, 55 g flour, mustard, 12 g salt, onion powder, garlic powder, five-spice powder, 4 g sugar, and 4 g MSG until well combined. Add chicken pieces and mix gently to coat. Cover and refrigerate chicken for at least 12 hours and up to 24 hours.

Make dry chile mix: Spread chiles in an even layer on a sheet pan and roast until slightly darker, aromatic, and brittle. Transfer to a heatproof surface and let cool. Toast Sichuan peppercorns until aromatic. Blend chiles and peppercorns until fine, then whisk in vinegar powder, sugar, salt, and MSG.

Make chile oil: Warm duck fat over medium heat until fully melted. Remove from heat, add canola oil and dry chile mix, and whisk until combined.

Make dredge: In a large bowl, whisk together remaining flour, potato starch, cornstarch, EverCrisp, salt, sugar, and MSG until well combined.

Set up frying station: Set up a dredging station with marinated chicken, bowl of flour mixture, and a wire rack set inside a sheet pan. Heat oil in a Dutch oven to 350 °F / 177 °C.

Dredge and fry chicken first time: Remove chicken from marinade, dredge in flour mixture, and fry until cooked through. Let chicken rest.

Double fry chicken: Return oil to 350 °F / 177 °C and fry chicken again until golden brown and crispy.

Douse chicken in chile oil and serve: Dip each piece of chicken in chile oil until evenly coated and serve immediately.