01 - Whisk together buttermilk, hot sauce, garlic powder, onion powder, salt, and pepper in a large bowl. Submerge chicken thighs completely, cover, and refrigerate for minimum 2 hours or overnight for maximum flavor penetration.
02 - Combine flour, cornstarch, paprika, baking powder, cayenne, salt, and black pepper in a shallow dish. Mix thoroughly to distribute spices evenly.
03 - Pour vegetable oil into deep fryer or heavy-bottomed pot. Bring temperature to 350°F, maintaining steady heat throughout frying process.
04 - Lift chicken from marinade, allowing excess liquid to drip off. Press each piece firmly into flour mixture, ensuring thick, craggy coating adheres to all surfaces.
05 - Lower coated chicken carefully into hot oil. Cook 6 to 8 minutes per piece, turning once halfway through, 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 and crisp.
07 - Blend mayonnaise with hot sauce for spicy variation, or use plain mayonnaise as preferred.
08 - Spread mayonnaise on toasted bottom buns. Layer lettuce, crispy fried chicken, tomato slices, and pickles. Crown with top buns and serve immediately while hot.