Beet Kvass for Borscht

Scrub the beets thoroughly with a brush, peel them, and cut into large slices or chunks — finely grated beets make the kvass cloudy, so the pieces should stay chunky and visible.

Place the beets in a clean three-liter jar, then add a slice of dried rye bread, salt, and sugar.

Pour in warm boiled water (35–40°C) so the beets are fully covered, leaving 3–4 cm of headspace below the jar's neck.

Cover the jar with cheesecloth folded into several layers (not a tight lid) and leave at room temperature, 18–22°C, for 3–5 days to ferment.

Every day, skim off any foam or film from the surface with a clean spoon and gently stir the contents of the jar.

The kvass is ready when it develops a pleasant tang and a rich burgundy color, and bubbling on the surface noticeably slows down — usually by day 4–5.

Strain the kvass through cheesecloth or a fine sieve, transfer it to a clean bottle with a lid, and store in the refrigerator for up to 2 weeks, adding it to borscht near the end of cooking for a natural tang and rich color without vinegar.