Drain sauerkraut. Heat oil in a large Dutch oven or large pot. Add onion; cook and stir until onion is tender. Add sauerkraut, potato, sugar, caraway seed, and water. Mix thoroughly.
Tie juniper berries, peppercorns, allspice, and bay leaves in a square of 100-percent-cotton cheesecloth; tuck bag under sauerkraut. Place meat atop sauerkraut mixture.
Bring the mixture to boiling; reduce heat. Cover and simmer for 45 minutes. Uncover and boil gently for 15 minutes or until most of liquid is evaporated. Remove seasoning bag. Remove meat and cut into 1/4-inch-thick slices. Transfer sauerkraut to a large platter and arrange sliced meat on top. Makes 4 to 6 servings.