Add all ingredients (starting with the lesser amount of water) to a high-speed blender and blend on high until creamy and smooth, scraping down sides as needed. If it has trouble blending, add more water.
Taste and adjust as needed, adding more mango for sweetness or lime juice for brightness!
Best when fresh. Leftovers can be stored in the refrigerator for up to 24 hours, or frozen into ice cube or popsicle molds and stored in the freezer for 1 month.
*To cook beets: Cube first then steam in a steamer basket, covered, until tender (about 10-15 minutes). Then freeze before using in smoothies. *Prep time assumes using already steamed and frozen beets. *Inspired by the rehydrator smoothie at Juiceland.