Dissolve rye sourdough starter in 1 cup of diluted malt mixture, stir, and pour it into the pot.
Keep at room temperature (72-74F) for about 2 days. It takes 12 hours when the temperature is 86F. At lower temperatures, fermentation process takes longer.
In 12 hours, 72F, the surface of kvass will be mostly covered with thick layer of foamy bubbles. Your kvass is ready to bottle when its taste is pleasantly sour, with an appetizing aroma.
Prepare two pint-sized clean screw-cap or flip-top bottles and funnel.
When bottling kvass, make sure the sediment on the bottom of the jar where kvass was fermenting is not disturbed. To carbonate kvass during the next step, conditioning, feed it with agave syrup right before bottling. Add 2-3 small raisins per 1/2 quart of kvass. Seal the bottles.