The beans are soaked in water overnight and then boiled until soft for 50 - 60 minutes and then drained.
Melt the butter, carefully brown the finely diced onion, add the flour, pour the meat stock, season with parsley, marjoram, salt and pepper. Stir well. Put the cooked beans in the sauce and let them steep again slowly over a low heat. If desired, refine with a little vinegar. The quantities given are variable.