01 - Combine chicken, pickle brine, and hot sauce in a resealable bag or bowl. Marinate in the refrigerator for at least 1 hour, up to overnight for maximum flavor penetration.
02 - Heat vegetable oil in a heavy-bottomed pot or deep skillet until it reaches 350°F. Maintain this temperature throughout frying for optimal crispiness.
03 - Whisk together flour, cornstarch, paprika, garlic powder, onion powder, cayenne pepper, kosher salt, and black pepper in a shallow dish until evenly combined.
04 - Remove chicken from brine, allowing excess liquid to drip off. Press each piece firmly into the flour mixture, coating completely on all sides. Shake off any excess breading.
05 - Fry chicken pieces in batches for 5-7 minutes per side until golden brown and cooked through. Internal temperature must reach 165°F. Transfer to a wire rack or paper towels to drain.
06 - Whisk mayonnaise and Dijon mustard in a small bowl until smooth and fully incorporated.
07 - Lightly toast the cut sides of brioche or potato buns until golden. Spread the mayonnaise-mustard mixture evenly on both halves.
08 - Place fried chicken on the bottom bun. Top with shredded lettuce and pickle slices. Cover with the top bun and serve immediately while hot.