01 - Combine buttermilk, hot sauce, salt, and black pepper in a large mixing bowl. Submerge chicken thighs and marinate for at least 20 minutes or refrigerate overnight.
02 - In a shallow dish, whisk together all-purpose flour, cornstarch, paprika, garlic powder, onion powder, cayenne pepper, and salt until thoroughly combined.
03 - Remove chicken from marinade, allowing excess liquid to drip off. Dredge each thigh in the seasoned flour mixture, pressing to ensure full coverage. Arrange coated pieces on a wire rack and rest for 10 minutes.
04 - Pour vegetable oil into a heavy skillet or Dutch oven to a depth of 1 inch. Preheat oil to 350°F using a thermometer for accuracy.
05 - Working in batches, fry chicken thighs 5–7 minutes per side or until exterior is deeply golden brown and internal temperature reaches 165°F. Drain on a wire rack.
06 - In a medium bowl, combine 1/2 cup hot frying oil with cayenne pepper, brown sugar, chili powder, smoked paprika, garlic powder, and salt. Whisk until homogeneous. Generously brush the hot sauce over each side of the fried chicken.
07 - If desired, spread unsalted butter on the cut sides of brioche buns and toast in a skillet until lightly browned.
08 - Place sauced chicken thigh on each bun base, layer with dill pickle chips and a generous serving of coleslaw, then cap with the top bun. Serve immediately.