In the same Dutch oven, brown the onion with the cumin. Deglaze with the wine and bring to a boil. Add the sauerkraut mixture, the roast and the bay leaf. Cover, reduce the heat and simmer gently for 90 minutes. Turn the meat and add the potatoes, pushing them into the cooking juices. Cover and continue cooking until the meat is fork tender, about 2 hours. Discard the bay leaf and adjust the seasoning.