01 - Whisk buttermilk, hot sauce, salt, pepper, garlic powder, and paprika in a bowl until combined. Submerge chicken thighs completely in the marinade. Refrigerate for at least 20 minutes, preferably overnight for maximum flavor penetration.
02 - Combine flour, cornstarch, salt, paprika, cayenne pepper, onion powder, and garlic powder in a large bowl. Stir thoroughly to distribute spices evenly throughout the flour mixture.
03 - Lift 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 and arrange on a wire rack.
04 - Pour vegetable oil into a deep skillet or Dutch oven to a depth of 1 inch. Heat oil to 350°F, monitoring with a thermometer to maintain consistent temperature throughout frying.
05 - Carefully place chicken pieces in hot oil without overcrowding. Fry for 5 to 7 minutes per side until golden brown and crispy. Verify internal temperature reaches 165°F. Transfer to wire rack to drain excess oil.
06 - Toss shredded cabbage and grated carrot in a bowl. Add mayonnaise and apple cider vinegar, mixing until vegetables are evenly coated. Season with salt and pepper to taste. Refrigerate until assembly.
07 - Lightly toast burger buns if desired. Spread mayonnaise on bottom halves. Layer with lettuce leaves, fried chicken thighs, coleslaw, and pickle slices. Cover with top bun and press gently.
08 - Arrange burgers on serving plates and serve immediately while chicken remains hot and coating stays crispy.