Heat the oil in a large, non-stick frying pan or wok and stir-fry the chicken and peppers for 2 mins. Sprinkle over the spices and cook for 30 secs more, stirring. Tip the tomatoes into the pan and stir in the chipotle paste. Simmer for 5 mins or until the sauce is thick and glossy, stirring regularly. Stir in the spring onions and coriander, cook for 1 min more, then remove from the heat and leave to cool.
Cut the tortillas into quarters, then cut each quarter into three pieces, so you have 36 triangles. Place 1 tsp of the chicken mixture and a little cheese at the widest end of a triangle. Roll the pointed end of the triangle around the filling and secure with a cocktail stick. Place on a baking tray lined with baking parchment. Fill and roll the other triangles. Cover with cling film and chill for up to 8 hrs until ready to reheat.
To make the dip, mash all the ingredients in a bowl until almost smooth. Cover the surface of the dip with cling film and chill for up to 24 hrs.
When ready to serve, heat oven to 200C/180C fan/gas 6. Uncover the fajitas and bake for 6-8 mins or until hot throughout. Serve with the guacamole.