Coarsely chop the beets into ½ - to 1-inch (1 to 2.5 centimeters) pieces. Cut the ginger (if using) into ¼-inch (6 milometer) chunks. Place the beets, ginger, and rosemary (if using) in a half-gallon (2 liter) Mason jar. Fill the jar halfway with filtered water. Add the salt, close the lid, and shake. Once the salt has dissolved, open the lid and fill with water to the shoulder of the jar, leaving 1 to 2 inches (2.5 to 5 centimeters) of space at the top. Close the lid. Write the date on a piece of masking tape and stick it to the outside of the jar.

Let it sit for a few days to 1 week, if your room is warm, or for 2 or 3 weeks if it’s cooler. The kvass will progress well, if you keep the lid closed. Gently agitate once a day to ensure that mold does not form. You know it’s on its way when it starts getting foamy. Once you open the lid, though, it’s best to strain the kvass and refrigerate it because if you close it again and leave it at room temperature, molds can take hold.

When you’re ready to put it into the fridge, pour it through a strainer to separate the beets (and other optional ingredients) from the liquid. The kvass is the liquid. Keep it covered in the refrigerator and drink it cold, if you like.

Keep the beet chunks in the refrigerator, too. They can be chopped up and thrown in salads or soups, blended and added to salad dressing, or put through a juicer. Or you can blend the beet chunks with some of the kvass as the base for a fermented beet gazpacho or borscht!

Variation: Substitute 6 carrots for the beets. (Ginger goes well in carrot kvass; rosemary may overwhelm it.) Carrot kvass is a good option for people who don’t like beets, and it’s a good way to start developing a taste for fermented tonics.

From: Kombucha, Kefir, and Beyond: A Fun & Flavorful Guide To Fermenting Your Own Probiotic Beverages At  Home © 2017 Quarto Publishing Group USA Inc. Text © 2017 Alex Lewin and Raquel Guajardo. Photography © 2017 Quarto Publishing Group USA Inc. First Published in 2017 by Fair Winds Press, an  imprint of The Quarto Group, 100 Cummings Center, Suite 265-D, Beverly, MA 01915, USA.