Preheat the oven to 200°C, gas mark 6. Line a large roasting tin with baking parchment or non-stick foil. Put the chicken, peppers and onion into the tin, add the tikka paste and 3 tbsp yogurt, and season, then rub together. Roast for 25 minutes, stirring after 15 minutes, until the chicken is cooked through and golden with no pink meat.
Mix the chopped tomatoes with the mint or coriander, lime juice and seasoning. Warm the wraps. When ready to eat, spread the wraps with yogurt, top with the chicken and vegetables, and a spoonful of tomato salad, then fold or roll up.