Steps
- Stir 5 liters of warm water, 150ml of kvass concentrate, and 1¾ cups of sugar in a large food-safe vessel until dissolved. Stir in 1½ teaspoons of active dry yeast.
- Add 10 raisins and ½ loaf of toasted rye bread, cut into 1in / 2.5cm pieces. Cover with a secured breathable cloth. Ferment at about 85°F / 29°C for 18-20 hours.
- Remove the bread and raisins. Strain through several layers of cheesecloth into sealable bottles, filling only three-quarters full. Refrigerate with the lids loose, then tighten once cold.