Prepare the Chicken and Marinade: Pat the chicken pieces thoroughly dry with kitchen paper. In a large bowl, combine the buttermilk. Add the chicken, ensuring each piece is fully submerged. Cover the bowl and refrigerate for at least 2 hours, or ideally 4 hours, to allow the chicken to tenderise and absorb the tangy flavour. You’ll notice the buttermilk thickening slightly and coating the chicken with a creamy texture.

Create the Herb and Spice Blend: In a wide, shallow dish or a large freezer bag, combine the plain flour, cornflour, smoked paprika, dried thyme, dried oregano, dried sage, garlic powder, onion powder, ground ginger, white pepper, black pepper, mustard powder, celery salt, salt, and cayenne pepper (if using). Whisk or shake until all the spices are evenly distributed, creating a fragrant, pale orange-tinged flour mix.

Dredge the Chicken: Remove the chicken from the buttermilk, allowing any excess to drip off gently. Do not rinse. Working one piece at a time, dredge the chicken thoroughly in the seasoned flour mixture. Press the flour onto the chicken firmly to ensure a thick, even coating. You want to see a shaggy, craggy texture forming, which will become our crispy crust. Place the coated chicken on a wire rack set over a baking tray while you coat the remaining pieces.

Heat the Oil: Pour the vegetable or rapeseed oil into a large, heavy-bottomed frying pan or a deep cast-iron pot. The oil should be deep enough to cover at least half of the chicken pieces. Heat the oil over medium-high heat until it reaches 175°C (350°F). You can test the temperature with a kitchen thermometer, or by dropping a tiny pinch of flour into the oil – it should sizzle immediately but not burn. You’ll notice a faint, almost sweet scent from the hot oil.

Fry the Chicken (First Batch): Carefully lower 2-3 pieces of coated chicken into the hot oil, ensuring not to overcrowd the pan. Listen for the satisfying sizzle as the chicken hits the oil. Fry for about 6-8 minutes per side, turning occasionally with tongs, until the coating turns a deep golden brown and sounds wonderfully crisp when gently tapped. The internal temperature should reach 74°C (165°F). You might see small bubbles vigorously dancing around the chicken.

Finish Frying and Rest: Once golden and cooked through, carefully remove the chicken from the oil and place it back on the wire rack over the baking tray to drain any excess oil. This allows the heat to redistribute and the crust to remain crisp. Repeat with the remaining chicken, ensuring the oil temperature returns to 175°C (350°F) between batches. Let the chicken rest for 5 minutes before serving, allowing the juices to settle for maximum succulence.