Marinate the Chicken: Place the chicken thighs in a shallow dish or a reusable food bag. In a separate bowl, whisk together the buttermilk, 1 tbsp of hot sauce, and 1 tsp of salt. Pour this mixture over the chicken, ensuring each piece is fully coated. Cover and refrigerate for at least 4 hours, or up to 24 hours for the most tender results.

Prepare the Spicy Mayo: While the chicken marinates, make the sauce. In a small bowl, combine the mayonnaise, 2-3 tbsp of hot sauce, garlic powder, and smoked paprika. Stir until smooth. Taste and add more hot sauce if you like it spicier. Cover and pop it in the fridge until you're ready to serve.

Set Up the Dredging Station: In a wide, shallow bowl or dish, whisk together the plain flour, cornflour, smoked paprika, garlic powder, cayenne pepper, black pepper, and salt. This is your spiced flour coating. Remove the chicken from the marinade, letting any excess drip off, but don't pat it dry.

Coat the Chicken: This is the most important step for a crispy coating! Take one piece of chicken and dredge it thoroughly in the spiced flour, pressing down firmly to make sure the flour adheres everywhere. Transfer it back into the buttermilk marinade for just a second, then dredge it *again* in the flour mixture, pressing firmly once more. This double-dredge creates an ultra-crispy crust. Set the coated chicken on a wire rack and repeat with the remaining thighs.

Heat the Oil: Pour the oil into a large, heavy-bottomed pan or Dutch oven until it's about 4-5 cm deep. Heat it over a medium-high heat to 175°C (350°F). What works best for me is using a cooking thermometer for accuracy, but you can test it by dropping a tiny bit of the flour mixture in – if it sizzles vigorously, the oil is ready.

Fry the Chicken: Carefully place 2 pieces of chicken into the hot oil, ensuring you don't overcrowd the pan. Fry for about 4-6 minutes on each side, until the coating is a deep golden brown and the chicken is cooked through. The internal temperature should reach 74°C (165°F) according to the Food Standards Agency.

Rest and Assemble: Remove the cooked chicken from the oil with tongs and let it rest on a clean wire rack. This allows excess oil to drip off and keeps the bottom from getting soggy. Repeat with the remaining chicken.

Build Your Sandwich: It's time to assemble your masterpiece! Lightly toast your brioche buns. Spread a generous layer of the spicy mayo on the bottom bun. Top with a piece of crispy fried chicken, a few dill pickle slices, and some crisp lettuce. Add the top bun and serve immediately while it's hot and crunchy.