cooked beets, roughly chopped
low-sodium vegetable broth
In a saucepan on medium high heat, saute onion until brown for 2 minutes. Using 1 tablespoon of oil is optional.
Add everything and reduce the heat to low and allow the mixture to simmer for 25-30 minutes. Stir often and remove from heat. Allow the mixture to cool.
In a high speed blender, place everything and blend until smooth in consistency.
The sauce can be kept for 10 days. Store in airtight containers in the refrigerator.