Heat butter over low heat in a large pot. Add onions and peppers and stir, cooking over medium-low heat until onions are translucent. Add minced garlic (optional) and cook while stirring for about one minute -- DON'T BROWN THE GARLIC! It will get bitter!
Stir in brown sugar. Add cabbage and continue to stir fry for 4 to 7 minutes to "sweat" the cabbage. Nita's Note: Sweating tenderizes cabbage and releases the flavor, otherwise it would take a long time to cook or tenderize it by boiling!
Add tomatoes, vinegar and chicken broth/stock and bring to a slow boil. Season with black pepper, to taste. Cook soup about 20 minutes, boiling gently, uncovered to combine flavors. Cabbage should be tender. DON'T OVERCOOK!
Add chicken broth or water if a thinner soups is desired. Taste and adjust seasoning with vinegar, brown sugar, black pepper, as needed. Serve hot with about a tablespoon of sour cream and a sprinkling of chives on top of each bowl if desired.
Note: May be halved for 2 or 3 people. Also can just cook cabbage and onions etc. as a side dish WITHOUT the chicken stock!
Nita Holleman, 2003