Step 1: Make the Marinade
In a large bowl, whisk together milk, vinegar, egg, salt, and 1 tablespoon of your spice mix to create the buttermilk marinade. Place chicken thighs between two sheets of baking parchment and gently flatten with a rolling pin until even in thickness. Add to the marinade, cover, and refrigerate for at least 4 hours or overnight.

Step 2: Prepare the Coating
In a large bowl, mix self-raising flour, cornflour, turmeric, most of the remaining spice mix (save 1 tsp for later), and a generous pinch of salt. Remove chicken from marinade, letting excess drip off, and dredge each thigh in the flour mix. Dip back into the marinade, then dredge once more, pressing the coating on firmly.

Step 3: Fry to Perfection
Heat 10cm of sunflower oil in a deep pan or fryer to 175°C. Carefully lower in 2–3 thighs at a time and fry for 3 minutes without disturbing. Flip and fry another 2–3 minutes, until golden and crispy. Keep oil temperature around 170°C to ensure crispiness. Transfer cooked thighs to a paper towel-lined tray, then to a wire rack in a low oven to keep warm.

Step 4: Finish and Serve
Mix the reserved 1 tsp spice mix with 1 tbsp flaky sea salt and sprinkle over the hot chicken just before serving for an extra flavor boost.