Peel and thickly slice the red onion. Halve the peppers and scoop out the seeds. Slice them into finger-sized lengths. Heat a frying pan for 1 min. Add 1 tbsp olive oil, the onion and peppers. Season. Fry for 8 mins till softened. Stir now and then.
While the peppers are cooking, peel and grate the garlic cloves. Halve the chipotle and flick out the seeds. Roughly chop it. Add half the garlic and all the chipotle to the peppers. Tip in the tinned tomatoes. Stir. Pop on a lid and simmer on a low heat for 20 mins till the sauce has thickened. No lid? Use a baking tray to cover the pan.
While the peppers cook, remove any large leaves from the cauliflower and discard them. Roughly chop it, and any tender leaves. Add to a food processor and pulse till the cauliflower looks like rice grains. No processor? Coarsely grate the cauli, tip it on to a board and chop it finely.
When the sauce has cooked for 15 mins, set a large frying pan or wok on a medium heat. Pour in 1 tbsp olive oil. Add the garlic and 2 tsp each dried oregano and cumin seeds. Cook for 1 min. Tip the cauli rice into the pan with a good pinch of salt. Stir fry for 5-7 mins till the cauliflower is tender.
While the sauce and cauliflower are cooking, halve the avocado. Scoop out the stone, then scoop the flesh from the skins. Finely slice it. Pick the leaves off the coriander stalks. Cut the lime into wedges.
Taste the tomato and chipotle sauce. Add 1-2 tsp sugar to taste and a little more salt and pepper, if you think it needs it.
Spoon the spiced cauli rice into bowls. Top with the pepper sauce. Arrange the avocado slices on top. Scatter over the chopped coriander and squeeze over the lime wedges.