Place all ingredients in a blender, and blend on high until smooth.
Pour into one or two glasses and top with frozen berries if desired.
Makes about 16 ounces, so one large or two small smoothies.
Notes
To make beet puree, peel and chop two beets. Place in a pan and cover with water, bring to a boil. Reduce heat to a simmer, then cook for about 20-30 minutes, or until beets are fork tender. Allow to cool fully, then puree in a food processor.