This is a great recipe if you love homemade barbecue sauce but can't use it all before it goes bad.
1/4 cup margarine/butter
2 large yellow onions, peeled & diced
1/2 cup Worcestershire sauce
1/2 cup cider or red wine vinegar
2 tbsp chili sauce or A1 sauce
1/4 cup sugar
4 cups water
Melt butter in a saucepan over medium heat, then saute onions until soft. Add remaining ingredients, cover and simmer for 20 minutes. Uncover, bring to a boil until it is reduced by 1/3. Allow to cool, strain to remove onion pieces, then freeze in 1-2 cup portions (or whatever portion size you find most convenient).
Either thaw in refrigerator or place sealed container in hot water. Then heat in saucepan or microwave, then use.