Place the chicken thighs into a shallow cooking dish. Mix the buttermilk and sriracha together and pour the mixture over the chicken. Leave to marinate for at least 6 hours or overnight.
On a plate, mix the chicken spices and whole wheat self-raising flour. Remove the chicken from the marinade and toss in the flour and spice mixture.
Place the chicken on a wire rack and leave for 15 minutes to rest. While the chicken is resting, slowly heat a shallow pan with sunflower oil.
Cut the potatoes and onion into wedges, cut the sweet red peppers into strips and add to an oven tray. Season with salt and pepper and drizzle with olive oil. Cook in the oven for 20-25 minutes until crispy.
Add the chicken to the shallow pan and fry on both sides until crispy and cooked through. If the chicken is too thick, place it in the oven with the vegetables for 10 minutes, until cooked through.
Serve the crispy chicken with the potato wedges, onions and red peppers.
