Add the first 10 ingredients into a medium saucepan and simmer for 45 minutes (or longer if you prefer a thicker sauce).
Measure the remaining ingredients into the BBQ sauce and blend with a stick blender (or use a blender) until smooth. Taste and adjust seasonings. Taste the next day and adjust further as it will mellow upon cooling. This results in a tangy sauce. (SEE BELOW FOR A VARIATION.)
Cool completely, pour into a clean air tight container, and refrigerate up to 10 days.
VARIATION: Saute the onions and garlic in 1 tbsp butter until softened, then add the rest of the ingredients. Add the remaining butter after cooking. This results in a more mellow flavored sauce.
Makes 2 1/2 - 3 cups. Serving size is 2 tbsp and is 1 net carb per serving.