01 - Combine chicken, pickle brine, and hot sauce in a resealable bag. Marinate in refrigerator for at least 1 hour, up to overnight.
02 - Pour vegetable oil into a heavy-bottomed pot or deep skillet. Heat to 350°F.
03 - Whisk together flour, cornstarch, paprika, garlic powder, onion powder, cayenne pepper, salt, and black pepper in a shallow dish.
04 - Remove chicken from brine, allowing excess to drip off. Press thoroughly into flour mixture, ensuring complete coating on all sides.
05 - Fry chicken 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 smooth.
07 - Lightly toast buns. Spread mayo-mustard sauce on both halves.
08 - Place fried chicken on bottom bun. Layer with shredded lettuce and pickle slices. Top with remaining bun half. Serve immediately.