Heat oven to 220C/200C fan/gas 7.
Put the sliced onion, lime juice and
seasoning in a bowl, and set aside.
Heat 1 tbsp of the oil in a pan and fry
the chopped onion and garlic until tender.
Stir in the cumin and fry for 1 min more.
Add the tomato purée, chipotle paste and
beans, stir, then tip in half a can of water.
Simmer for 5 mins, season, then roughly
mash to a purée. (You can cook for a few
mins more if it is a bit runny, or add a few
splashes of water to thin.)
Meanwhile, brush the tortillas with
the remaining oil and place on a baking
sheet. Bake for 8 mins until crisp. Spread
the tortillas with the bean mixture.
Mix the radishes and coriander with
the pickled onions, then spoon on top.
Serve with lime wedges.