Cut the chicken, breast lengthways, and place in the bowl with the paprika, chilli powder, sugar, lime zest and juice and the chilli oil. Cover and leave to marinate for a couple of hours. Thread 2 pieces of chicken onto each soaked skewer. Place under the grill for 2-3 minutes on each side.
For the guacomole, combine all the ingredients, mix well and season to taste. Assemble and serve the skewers with the tomato and avocado salsa, warmed tortillas, lettuce and soured cream.