For juicier results, marinate chicken in buttermilk + hot sauce for at least 4 hours or overnight. (Optional but highly recommended.)
Make the Dry Mix:
In a large bowl, whisk together flour, cornstarch, salt, pepper, paprika, garlic powder, onion powder, cayenne, and baking powder. Set aside.
Make the Wet Batter:
In a separate large bowl, whisk together eggs, buttermilk, water, hot sauce, and mustard if using.
Dredge Chicken:
Remove chicken from marinade (if marinated).
Dip each piece into the dry flour mix, then into the wet batter, then back into the dry mix, pressing the flour mixture onto the chicken to form a thick, craggy crust.
Rest the Chicken:
Let coated chicken sit on a rack or tray for 10–15 minutes before frying. This helps the crust stick.
Fry the Chicken:
Heat oil (preferably peanut, canola, or vegetable oil) to 325–350°F (163–177°C) in a deep fryer or large heavy pot.
Fry in batches, 10–15 minutes depending on piece size, until golden brown and internal temp hits 165°F (74°C).