Start by making the chilli salsa as it is best served chilled. Chop the tomatoes into small pieces, removing any seeds. Put them in a bowl, along with all the remaining ingredients. Season well with pepper and salt, mix well, and leave to infuse in the fridge while you prepare the chicken. Mix the paprika and cumin together and rub into the chicken slices. Heat the oil in a pan and add the spiced chicken pieces. Cook for 2 minutes, before adding the sliced onion and peppers. Season with pepper and salt, and continue to cook for 2 more minutes. The chicken should be soft but the onions and peppers should still be firm. Heat the tortilla wraps in the oven or grill, and then lay them out on your serving plates. Spread the sour cream all over the wraps, followed by a generous portion of the chilled tomato salsa. Next, add the chicken fajita mixture and finally sprinkle with the grated cheddar cheese. Roll up the tortilla wraps tightly, and serve with some of the remaining tomato salsa. You can alternatively serve the fajitas with tortilla chips.