01 - Whisk together buttermilk, hot sauce, garlic powder, onion powder, salt, and pepper in a large bowl. Add chicken thighs, submerging completely. Cover and refrigerate for at least 2 hours, preferably overnight for maximum flavor penetration.
02 - Combine flour, cornstarch, paprika, baking powder, cayenne, salt, and black pepper in a shallow dish. Whisk thoroughly to ensure even distribution of spices and leavening agents.
03 - Pour vegetable oil into a deep fryer or heavy-bottomed pot. Heat to 350°F, maintaining temperature throughout frying for optimal crispiness and even cooking.
04 - Remove chicken from marinade, allowing excess liquid to drip off. Press each piece firmly into the flour mixture, turning to coat completely and creating a thick, craggy coating that will crisp beautifully.
05 - Carefully lower coated chicken into hot oil using tongs. Fry for 6-8 minutes per piece, turning once halfway through, until golden brown and cooked through to an internal temperature of 165°F. Drain on a wire rack or paper towels.
06 - Lightly toast burger buns until golden, creating a sturdy base that won't become soggy from the sauce and juices.
07 - Combine mayonnaise with hot sauce in a small bowl, adjusting heat level to preference. This adds a complementary kick to the rich fried chicken.
08 - Spread spicy mayo on the bottom bun. Layer with lettuce, followed by the hot fried chicken fillet. Top with fresh tomato slices and dill pickles. Crown with the top bun and serve immediately while chicken remains crispy.