To make the beans, heat the oil in a pan and fry the onion for 5 mins until soft. Add both types of beans, the passata, chipotle paste, vinegar and sugar and simmer for 15 mins until thick and saucy. Season. Add more chipotle paste, sugar or vinegar to taste – it should be a balance of sweet, spicy and tangy. To make the salsa, combine all of the ingredients and season.
Heat the oil in a large frying pan and fry the peppers and mushrooms for 10 mins until soft. Squeeze small chunks of sausagemeat from the sausage skins into the pan and fry for 10 mins more until golden and cooked through.
Warm the tortillas, then keep warm in a clean tea towel. Put the avocados, coriander, cheese and lime wedges (if using) in bowls.
Just before serving, make the scrambled eggs. Heat the butter in a pan and add the cumin seeds. Sizzle for 1 min, then add the eggs, stirring slowly, until scrambled. Season and tip into a warmed bowl. Serve everything in the middle of the table with chilli sauce, if using, and let everyone dig in.