Marinate the Chicken:
Combine buttermilk, hot sauce, and vinegar in a bowl. Add chicken pieces, cover, and refrigerate for at least 12 hours.
Prepare Dry Rub:
Mix flour, cornstarch, and spices (salt, black pepper, cayenne, garlic powder, paprika, thyme, Cajun seasoning).
Prepare Wet Batter:
Combine water or milk with a portion of the seasoned flour mixture to form a thick batter.
Coat the Chicken:
Remove chicken from marinade. Coat in dry rub, dip in wet batter, and coat again with dry rub for a double dredge.
Fry the Chicken:
Heat oil to 350°F in a deep pan. Fry chicken in small batches for 12-15 minutes or until golden and internal temperature reaches 165°F.
Bake Alternative:
Preheat oven to 400°F. Arrange coated chicken on a baking sheet and bake for 25-30 minutes.
Rest and Serve:
Let fried chicken rest on a wire rack to stay crispy. Serve hot with desired sides and dipping sauces.
