01 - Whisk together buttermilk, hot sauce, garlic powder, onion powder, salt, and black pepper in a large bowl. Submerge chicken thighs completely, cover, and refrigerate for 2 hours or overnight.
02 - Combine flour, cornstarch, paprika, baking powder, cayenne pepper, salt, and black pepper in a shallow dish.
03 - Pour vegetable oil into a deep fryer or heavy-bottomed pot. Heat to 350°F.
04 - Lift chicken from marinade, letting excess drip off. Press each piece firmly into flour mixture, coating completely and creating a thick, craggy layer.
05 - Lower coated chicken into hot oil carefully. Fry 6 to 8 minutes per piece, turning once, until deep golden brown and internal temperature reaches 165°F. Transfer to wire rack to drain.
06 - Lightly toast cut sides of burger buns until golden.
07 - Blend mayonnaise with hot sauce in a small bowl for spicy mayo variation.
08 - Spread mayonnaise on bottom buns. Layer lettuce, fried chicken, tomato slices, and pickles. Crown with top buns and serve immediately.