Instructions:
- Brine the Chicken: Combine buttermilk, hot sauce, salt, and pepper in a container. Submerge chicken thighs completely. Cover and refrigerate for at least 2 hours, ideally 4–8 hours.
- Prepare the Honey Mustard: Whisk together all sauce ingredients (mayonnaise, Dijon, honey, vinegar, paprika, salt, pepper) until smooth. Set aside.
- Prep the Dredge: In a wide, shallow bowl, thoroughly combine all dry coating ingredients (flour, cornstarch, spices, salt, pepper).
- Coat the Chicken: Remove chicken from the brine, letting excess drip off. Dredge each piece vigorously in the flour mixture, pressing firmly to ensure a thick coating. For extra crunch, dip briefly back into leftover buttermilk, then back into the flour mixture.
- Heat the Oil: Pour oil into the Dutch oven to a depth of 1.5 to 2 inches. Heat over medium-high heat until the oil registers 325°F (160°C).
- Fry the Chicken: Carefully lower 1-2 pieces of chicken into the oil. Maintain the oil temperature between 300°F and 325°F. Fry for 6–8 minutes per side until deep golden brown and cooked through (internal temperature of 165°F / 74°C).
- Drain and Rest: Remove chicken and place immediately on a wire rack set over a baking sheet. Season lightly with fine salt while hot. Let rest for 5 minutes.
- Toast Buns: Lightly butter the cut sides of the brioche buns and toast them face-down in a dry skillet until golden brown.
- Assemble the Sandwiches: Slather the top and bottom buns generously with the Honey Mustard Sauce. Place pickles on the bottom bun, top with the hot fried chicken thigh, and finish with the top bun. Serve immediately.