Drain and rinse the beans. In a large enameled cast-iron casserole, combine the beans with the water, ham hocks, onion, bell pepper, garlic, vinegar, black pepper, thyme, bay leaf and cayenne. Bring to a simmer over moderate heat. Cover partially, reduce the heat to moderately low and cook, stirring occasionally, until the beans are tender, about 1 1/2 hours. Add the ham, andouille and scallions and cook over moderate heat until the beans are just beginning to fall apart and the sauce is reduced to a thick gravy, about 30 minutes.
Remove the ham hocks. Pull the meat off the bones, tearing it into pieces. Return the meat to the beans and season with salt. Serve hot.