Gently mix in chopped cabbage. Bring mixture to a boil. Cover skillet, reduce heat and simmer for 15 minutes. Stir, recover, then simmer for 10 minutes longer, or until cabbage is tender.
Remove lid and add tomato paste. Stir and simmer, uncovered, for 5-10 minutes, or until sauce reduces slightly.
If you prefer a thicker sauce, add additional tomato paste and stir. Serve.