Stir in the can of tomatoes, bring to the boil, and turn down to simmer for 2 minutes then add salt, tomato puree, curry powder, ground cumin and ground coriander. Stir well together and simmer for a further 3 minutes.
Add all the beans. Stir well together. Then add coconut milk. Cover the pan and allow to gently simmer for 10 minutes. Stirring occasionally.
Serve this black bean curry with rice or naan breads, garnished with the coriander and a lemon wedge each.