Sweet and Sour Sauerkraut

1 large can sauerkraut
1 cup catsup or tomatoes
1/2 cup brown sugar
1/2 cup (1 stick) butter
1 large onion

Saut� onion in margarine. Add a large can of sauerkraut that has been rinsed and drained. Add brown sugar, catsup, salt and pepper to taste, and simmer for at least 45 minutes.