Step 1: Prepare the Chicken:
Pat the chicken thighs dry with paper towels. In a shallow dish, whisk together the flour, cornstarch, paprika, garlic powder, onion powder, cayenne pepper, thyme, oregano, salt, and black pepper. In another shallow dish, combine the buttermilk and beaten egg.
Step 2: Bread the Chicken:
Dredge each chicken thigh in the flour mixture, ensuring it's fully coated. Dip it into the buttermilk mixture, then dredge it again in the flour mixture, pressing to ensure the breading adheres well. Place the breaded chicken on a wire rack while preparing the oil.
Step 3: Fry the Chicken:
Pour vegetable oil into a large, heavy-bottomed skillet to a depth of about 1 inch. Heat the oil over medium-high heat until it reaches 325-350F (160-175C) using a thermometer. Carefully place two chicken thighs into the hot oil, being careful not to overcrowd the pan. Fry for 6-8 minutes per side, until golden brown and cooked through. Remove the chicken and place it on a wire rack to drain excess oil. Repeat with the remaining chicken.
Step 4: Make the Hot Sauce:
In a small bowl, whisk together the melted butter, hot sauce, brown sugar, and garlic powder. Adjust the amount of hot sauce to your preferred spice level.
Step 5: Sauce the Chicken:
Brush or dip each fried chicken thigh in the hot sauce, ensuring it's evenly coated.
Step 6: Assemble the Sandwiches:
Lightly toast the brioche buns. Place a sauced chicken thigh on the bottom bun, top with coleslaw and dill pickle chips, and cover with the top bun. Serve immediately.
For a milder flavor, reduce the amount of cayenne pepper in the breading and hot sauce. Substitute coleslaw with lettuce and tomato if preferred. For an extra crispy crust, double-fry the chicken: Fry for 4 minutes per side, let cool slightly, then fry again for 2-3 minutes per side.