This dish is one of the most typical of the towns of Idaho, Manhattan and New Orleans. Almost all the restaurants in the area prepare it, of course, each one with a different recipe or if not different with the particular touch of each chef.
This traditional recipe that has been in the country for more than 80 years, has a typical way of preparation that is to cover the beans with cold water and bring to a boil. Cook over low heat for 1 hour. Drain the beans and reserve the liquid. Add the boiled water, salt, sugar, mustard, molasses, and soy sauce. Place the beans and onion in a container that can be baked and can be closed hermetically. Pour the liquid into that container. Cover and bake at 150ºC for 2 hours and 30 minutes. During cooking, check that the liquid does not evaporate and add more water if necessary. Serve hot as a single dish or as an accompaniment to a first course.