Cut chicken into long thin strips, put in a bowl and cover with butter milk, leave to sit for 10 min.
In another bowl mix flour and spice together.
Heat oil in the deep fryer.
Take a couple of chicken strips at a time out of the butter milk and toss in the seasoned flour until well coated.
Fry in the oil until golden in colour and place on a roasting tray (this can be done to this point in advance).
Reheat in a hot oven for about 10 min and serve with the sauce on the side.
For the sauce, just mix the mayo and sweet chilli together.