1. Grind all the rub ingredients except the oil in pestle and mortar. Rub into the chicken – you may want to put the rub and chicken into a freezer bag and shake around well. Chill for at least 30 minutes.
2. Preheat the oven to 150C/300F/gas 2. Place the fillets on a baking dish and rub with the oil. Roast for 45 minutes; remove from the oven and leave to cool.
3. The salsa can be made ahead and stored in the fridge. Preheat the grill (or fan grill if you have it) to 200C/400F. Wash and dry the tomatoes, cut them in halves and place on a lightly oiled baking tray. Scrape the seeds from the chilies if you like: I left one with the seeds in and the heat was moderate. Add them to the tray, skin side up. Peel and quarter the onion and add it to the tray with the garlic cloves. Grill for 15 minutes until the tomato skins are lightly scorched but not too burnt. Remove from the oven, peel off the skins that come off easily and leave everything to cool down a little.
4. Scrape it into the blender or food processor, add the sugar, lime juice and chopped coriander and pulse until smooth. Heat up a large saucepan with the 2 tbsp. of oil over medium heat. When the oil is hot, pour in the salsa carefully to avoid oil spitting and turn the heat down to low. Simmer for 20 minutes, stirring occasionally. Add the salt, taste if it needs more sugar or lime – it should be tart but not bitter. Decant to a bowl or container – if not used immediately, the salsa will keep in the fridge for a few days.
5. When you’re ready to assemble enchiladas, lightly grease a large (20 x 30cm) baking dish and spread a thin layer of salsa at the bottom. Preheat the oven to 180C/350F/gas 4. Peel the skin off the chicken fillets and shred the meat against the grain.
6. Heat up a dry skillet over medium heat. Place each tortilla in the skillet for a minute on each side until softened and lightly coloured. Spread a little salsa over it, add about 2 tbsp. of shredded chicken in a line in the middle, sprinkle about 1 tbsp. of grated cheese over chicken and roll up the tortilla tightly.
7. Place it in the prepared dish and continue with all the tortillas; they should be snug next to each other in the dish. Spread the remaining sauce over the enchiladas, sprinkle with half the remaining cheese and cover tightly with aluminium foil.
8. Bake for 15 minutes; take off the foil and top with the rest of the cheese. Bake for further 10 minutes until the cheese is melted and bubbly. Serve with dollops of cream or crème fraiche, quartered avocados and green salad.