Kvass is an excellent probiotic-rich health tonic and is great for digestion.
2 medium beets, washed well
1/4 cup whey* (optional)
2 teaspoons sea salt (4 teaspoons if omitting whey)
2 quarts filtered water
Cut beets into half inch chunks and place in half-gallon jar or divide between 2 quart jars. Add whey and salt, and fill with water until 1 inch from top of jar. Cover and allow to sit at room temperature for 1 week. Check periodically and skim off any whitish “scum.” Transfer to refrigerator.
When most of the liquid has been consumed you can refill the jar and allow to culture at room temperature again for a second, weaker batch. You can then save the beets to add to salads.
*You can make your own whey by draining plain yogurt in a cheescloth-lined colander. The resulting liquid is whey that can be used for making all kinds of cultured vegetables.