Soak the beans overnight. Cook the meat, potatoes, beans and sauerkraut separately. Bone the meat when it is done and cut into 1/2" cubes. Dice the potatoes. Crush the beans. Make a roux with the oil, flour & onion. Put meat & vegetables into a pot, add the roux, and the bay leaves. Cover with the stock & cook 10 minutes more. Before serving, add the yogurt.