Wash the beans and soak in water with the green pepper. When the beans swell, cook in the same water until soft. (45 minutes. approximately). Heat the oil in a frying pan and add onion, garlic, followed by ground green pepper. Add 1 cup of the beans to the pan and mash. Add this to the remaining beans together with the salt, pepper, bay leaf and sugar. Allow to boil for a further hour and add the vinegar and wine cooking slowly for another hour. If there is still too much liquid, cook uncovered for a while. Add 2 tbs. of oil just before serving.