Heat the olive oil in a frying pan over a medium heat and gently fry the garlic and chipotle paste for 1 minute, then add the beans, the tomatoes and 100 milliliters (1/2 cup) water. Season well with salt and pepper and bubble for 15 minutes until thickened and no longer raw-tasting.
Add the prawns and cook for 1 to 2 minutes until they are pink all over.
Meanwhile, mix the avocados with the onion and lime juice. Season well, drizzle over the extra-virgin olive oil and stir in half the cilantro.
Scatter the rest of the cilantro over the bean and prawn stew and serve with the salsa.