Add chicken thighs to a bowl with buttermilk. Season with salt and pepper, and mix. Let it marinate while you prep everything else.
In another bowl, mix the plain flour, cornflour, and 6 tablespoons of Harry’s Fried Chicken Spice. The cornflour helps the coating stick and gives it a crispier finish.
Take the chicken out of the marinade and press each piece firmly into the spice mix until fully coated. Set aside on a plate.
To make the mayo, crack one whole egg into a tall jug. Add the oil and blend with a stick blender until thick.
Add vinegar, lemon juice, and Very Peri Spice to the mayo. Blend again until smooth and creamy.
Heat your oil in a deep pan or pot. You want it between 140–160°C. Too hot and the coating will burn before the chicken is cooked through.
While the oil heats, slice your tomatoes, break up the lettuce, and butter your burger buns.
Fry the chicken in batches (2 pieces at a time) until golden and cooked through. Internal temp should reach 74°C. Set aside on paper towel.
To assemble: start with lettuce and tomato, add the crispy chicken, drizzle generously with the Peri Peri mayo, and close the lid.
Take a bite and enjoy the crunch, heat, and flavour!