Soak the pork belly in water for 3 hours. In the meantime, soak the red beans for 2 hours in 4 quarts warm water. Place them on the heat and bring to a boil slowly. Boil for 15 minutes, then throw away their water and replace with the same quantity of freshly boiled water. Cover and simmer. Place the meats in a heavy casserole and cover with cold water. Bring to a boil, skim. Add the onions, garlic, bouquet garni and simmer for 1 hour and 30 minutes, when the water will have evaporated by half. Drain the beans and add to the meats. Add boiling wine, pepper, nutmeg, sugar and cover. Simmer for 40 minutes. By now the beans should be tender, but not breaking up. Work the butter and flour together, and stir bit by bit into the beans, off the heat. Stir again, bring to a boil, taste, add salt if necessary and simmer until serving time. To serve, discard the bouquet garni, carve the meat and serve them on a layer of beans.