Black beans don't have  a strong flavour of their own but they do carry other flavours well. If you forget to soak the beans overnight, bring them up to the boil for 10 minutes and then pre-soak them for three hours. Serving salsa with the soup makes a clever contrast of the cold refreshing textures of the vegetables and the hot lusciousness of the soup.

I find that removing some beans for the salsa makes the soup too thin and you have bits of vegetables and pancetta in it. If the salsa is needed prepare beans separately (I generally have a few spare in the freezer). 

You will also need a large saucepan of about 6 pint (3.5 litre) capacity.

1. It's best to start the soup the night before by throwing the beans into a pan and covering them with about twice their volume of cold water. Next day, drain them in a colander and rinse them under a cold running tap. Now take the saucepan and heat the olive oil. As soon as it's really hot, add the chopped pancetta and cook for about 5 minutes. Then turn the heat down to medium, stir in the onion, garlic, carrot, swede and coriander stalks and continue to cook for another 10 minutes with the lid on, stirring everything round once or twice.
2. While that's happening heat a small frying pan over a medium heat, then add the cumin seeds and dry roast them for 2-3 minutes until they become very aromatic, begin to change colour and start to dance in the pan. At that point remove them from the pan and crush them to a coarse powder with a pestle and mortar. Add this to the vegetables along with the drained beans, Tabasco sauce and stock (but no salt at this stage), then bring everything up to a gentle simmer for about 1½ hours with the lid on. It's very important to keep the simmer as gentle as possible, so you might need to use a heat diffuser here.
3. When the time is up, use a slotted spoon to remove 3 level spoonfuls of the beans, rinse and drain them in a sieve and reserve them for the salsa. Now you need to purée the soup and the best way to do this is in a liquidiser – if not, a processor and a sieve will do, or even just a sieve. When the soup is liquidised, return it to the saucepan, add the lime juice, season with salt and pepper and it's now ready for re-heating later when you want to serve it.
4. To make the salsa, pour boiling water over the tomatoes, leave them for 1 minute, then slip the skins off, cut them in half and gently squeeze each half in your hand to remove the seeds. After the seeds are removed, chop the tomato into small dice and place it in a bowl along with the reserved beans, the finely chopped red onion, chilli, reserved coriander leaves and the extra virgin olive oil. Then add the juice of half a lime, some salt and freshly milled black pepper and leave it aside for the flavours to mingle and be absorbed for about 1 hour.
5. To serve the soup, re-heat it very gently being careful not to allow it to come to the boil, as boiling always spoils the flavour of soup. Serve in warm soup bowls, adding a spoonful of crème fraîche and an equal portion of salsa sprinkled over the surface.