Place the chicken on a chopping board, cover with baking paper and lightly pound to flatten with the smooth side of a meat mallet or with a rolling pin. Cut in half.
Place the coriander, paprika, cayenne and onion powder, pepper, salt, sugar in a large bowl along with the flour and mix to combine. Transfer the chicken to a glass bowl, sprinkle on 2 teaspoons of the spice rub and rub it onto the chicken. Cover with plastic wrap and marinate for 30 minutes.
Heat the oil in a large saucepan, wok or deep fryer to 180°C and line a large tray with paper towel and set a wire rack on top.
Combine the buttermilk and eggs in a shallow bowl and whisk with a fork. In another shallow bowl, combine the flours and the remaining seasoning with the remaining spice rub. Start a production line by first dipping the chicken pieces in the buttermilk mixture and then in the flour mixture. In batches of three pieces at a time, carefully lower the chicken into the hot oil and cook for 3–4 minutes on each side until a deep golden colour. Remove with a slotted spoon, place on the wire rack.
In a blender, puree the capsicum until smooth. Now add the paprika, mayonnaise, vinegar and lemon juice, and blitz again.
Warm the bread rolls up in a moderately heat oven and cut in half. Smear the sauce over each of the cut side of the bread roll, add the two pieces of crunchy chicken and then salad.