01 - Combine chicken, pickle brine, and hot sauce in a resealable bag. Refrigerate for at least 1 hour, up to overnight.
02 - Whisk together flour, cornstarch, paprika, garlic powder, onion powder, cayenne, salt, and pepper in a shallow dish.
03 - Pour vegetable oil into a heavy-bottomed pot or deep skillet. Heat to 350°F.
04 - Remove chicken from brine, allowing excess to drip off. Dredge thoroughly in flour mixture, coating all sides.
05 - Fry chicken pieces in batches for 5–7 minutes per side until golden brown and internal temperature reaches 165°F. Drain on wire rack.
06 - Mix mayonnaise and Dijon mustard in a small bowl until combined.
07 - Lightly toast buns and spread mayo-mustard sauce on both halves.
08 - Place fried chicken on bottom bun, top with lettuce and pickle slices, and cover with bun top. Serve immediately.