Roast in preheated oven for about 20-25 minutes, or until beets are tender and garlic is golden. If garlic is done before the beets, remove to plate and continue baking beets. Let the garlic and beets cool.
Once beets and garlic have cooled, add them and all remaining ingredients to a food processor. Blend until smooth. Add water 1 tbsp at a time to reach desired consistency.