Cut sausage into 2 - inch pieces. Place sausage with water to cover in a large Dutch oven; bring to a boil. Reduce heat; cover and cook 10 minutes or until thoroughly heated. Remove from water; set aside, and keep warm.
Combine sauerkraut, water, caraway seeds, and salt in a medium Dutch oven. Bring to a boil; reduce heat, and simmer 10 minutes. Stir in potato; simmer 3 minutes.
Sauté onion in hot shortening in a small skillet until tender. Stir in flour; cook 1 minute. Spoon onion mixture into sauerkraut mixture, stirring well. Cook over medium heat, stirring constantly, 3 to 5 minutes or until thickened and bubbly. Spoon mixture into a serving dish; top with reserved sausage pieces. Serve immediately.
Note: Pumpernickel bread may be served with this dish.