First marinate the chicken. Season the slices with salt and pepper. Put the lime zest and juice, orange zest, chillies, tequila and triple sec, if using, in a bowl and add the slices of chicken.
Toss and cover, then leave in the fridge for at least an hour or overnight.Remove from the fridge half an hour before cooking.
Roughly chop the coriander and put it in a food processor or blender with the lime juice.Process until you have a green-flecked sauce. Set aside.
Put the sliced red onion in a small bowl and cover with half the lime juice and plenty of salt. Leave to stand until the onion has turned bright pink.
Put a generous pinch of salt in a separate bowl and add the remaining lime juice.Mash in the avocado to make a rough guacamole.
Heat the oil in a large sauté pan. Add the onion wedges and green pepper and cook over a medium-high heat until they have started to soften and brown. Add the garlic, cumin seeds, cinnamon and chilli paste and stir for a couple of minutes.
Strain the chicken from the marinade and add it to the pan. Sauté over a high heat until cooked through. Add the coriander and lime sauce and toss to coat the chicken. Leave the pan on the heat until the sauce is just heated through.
Serve the chicken with the warmed tortillas and guacamole, garnished with the drained red onion slices, chillies, coriander leaves and lime wedges.