Put the rice in a medium saucepan with 600ml cold water and a pinch of salt if you like. Bring to the boil, then turn the heat down low, cover and gently simmer for about 20 mins until all the water has been absorbed. Turn off the heat and leave for another 10 mins undisturbed. Stir the rice and add the coriander and lime juice.
For the black beans, heat the oil in a large frying pan and add the garlic, chipotle, cumin, sugar and vinegar, and cook everything for 1 min. Tip in the beans and tomatoes, give everything a stir and simmer, uncovered, for 20 mins until thickened.
For the salsa and guacamole, mix the tomatoes with the onion, coriander, lime juice and seasoning. Tip half the salsa into another bowl and mash the avocados into it to make guacamole. Wrap everything up together in warmed wholemeal tortillas topped with natural yogurt, lime juice and grated cheese, if you like.