Reuben Casserole

1 cup sour cream
1/2 onion, chopped
16 ounces sauerkraut, drained, squeezed and rinsed
1 can corned beef
8 ounces grated Mozzarella cheese
1/2 loaf Beefsteak rye bread, cubed
1 stick margarine, melted

Layer in a 9-by-12-inch baking dish: sour cream, onion and sauerkraut as bottom layer. Next layer, crumble corned beef; then a layer of Mozzarella cheese; next, rye bread cubes. Finally, drizzle melted margarine over the top of casserole. Bake at 350 degrees for 30 minutes.