01 - In a large mixing bowl, blend buttermilk, hot sauce, kosher salt, and black pepper. Add chicken thighs, ensuring thorough coating, and marinate for at least 20 minutes, or up to overnight in the refrigerator.
02 - In a shallow dish, combine all-purpose flour, cornstarch, paprika, garlic powder, onion powder, cayenne pepper, and salt. Mix thoroughly to ensure even seasoning.
03 - Remove chicken from the marinade, letting excess liquid drip away. Coat each thigh in the flour mixture, pressing firmly to adhere. Arrange on a wire rack and rest 10 minutes.
04 - Pour vegetable oil into a heavy skillet or Dutch oven to a depth of 1 inch. Heat over medium-high to 350°F (175°C).
05 - Fry chicken thighs in batches, 5 to 7 minutes per side, until golden, crisp, and internal temperature reaches 165°F (74°C). Transfer to a wire rack to allow excess oil to drain.
06 - In a medium bowl, whisk 1/2 cup of hot frying oil with cayenne pepper, brown sugar, chili powder, smoked paprika, garlic powder, and salt until fully combined. Brush generously over both sides of the fried chicken.
07 - If desired, spread unsalted butter on the cut sides of the brioche buns and toast in a skillet until lightly golden.
08 - Layer sauced fried chicken on each bun base. Top with dill pickle chips and a generous amount of coleslaw. Place the top bun and serve immediately.