Make the marinade for the chicken by grating the lime zest into a shallow bowl. Cut the limes in half. Squeeze the juice from 3 halves into the bowl. Add the cayenne pepper and olive oil. Mix well. Add the chicken. Leave for 10 minutes.
Cut each pepper in half and pull out the core and stalk to deseed. Cut into thin slices and place in a mixing bowl. Peel and thinly slice the onion. Add to the peppers, with garlic and oil and mix. Leave until ready to cook.
To make the guacamole first cut the avocados in half. Remove the stones and scoop out the flesh. Gently mash with a fork to make a lumpy purée. Stir in the garlic with the juice from the remaining half lime and the cayenne pepper. Stir the cherry tomatoes into the guacamole
Heat the oil in a large non-stick pan over a medium heat. Cook the chicken, stirring occasionally until the pieces are browned and cooked through (usually about 7 minutes). There should be no trace of pink flesh and the juices must run clear. Transfer to a serving bowl.
Stir-fry the pepper mix for 2 minutes until it is lightly coloured but still crunchy. Wrap the chicken, guacamole and peppers in the warm tortillas.
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Try our ready-made version - Tesco chicken fajitas.
For top tips on protecting you and your family when preparing raw meat and poultry, visit Food Safety in the Home and view the full Food safety at home video.