01 - Combine chicken pieces with pickle brine and hot sauce in a resealable bag or bowl. Refrigerate for at least 1 hour, up to overnight for maximum flavor penetration.
02 - In a shallow dish, whisk together flour, cornstarch, paprika, garlic powder, onion powder, cayenne pepper, kosher salt, and black pepper until evenly distributed.
03 - Pour vegetable oil into a heavy-bottomed pot or deep skillet. Heat to 350°F, maintaining temperature throughout frying process.
04 - Remove chicken from marinade, allowing excess liquid to drip off. Press each piece firmly into the flour mixture, ensuring complete coverage on all sides. Shake off excess coating.
05 - Carefully place chicken pieces in hot oil, working in batches to avoid overcrowding. Fry 5-7 minutes per side until golden brown and internal temperature reaches 165°F. Transfer to wire rack to drain.
06 - Whisk together mayonnaise and Dijon mustard in a small bowl until smooth and fully combined.
07 - Lightly toast buns until golden. Spread prepared mayonnaise-mustard mixture on both cut sides.
08 - Place fried chicken on bottom bun, layer with shredded lettuce and pickle slices. Top with remaining bun half. Serve immediately while chicken remains crispy.