1 kg Russian rye bread (~ 2 lb)
6 liters boiling water (1.5 gallon)
25 g fresh yeasts (1 pack)
1 tbsp wheat flour
0.5 cup cut mint greens
300 g (2/3 lb) sugar
Glass bottles or cans
2 large sauce-pans
Clean fabrics - 2 separate pieces
Cut the rye bread into small cubes, place in one layer on baking sheets.
Pre-heat an oven to 380-400 F (160-180 C), and dry the bread pieces in the oven until they turn crunchy, but not burned.
Place the rye croutons in a large enameled or glass dish, pour 6 l (1.5 g boiling water) over them, stir, and let sit for about 10 hours at room temperature, then, sift with the fabrics in a colander.
Blend 1 pack of yeasts and 1 tbsp flour in 1 cup of this liquid and let sit in a warm place until it starts to get bubbles.
Boil another two cups of this liquid with the mint, boil for 1 minute, and dissolve all the sugar in it.
Pour the yeast-flour-liquid mix in the liquid, then pour the mint-sugar-liquid mix in it, stir well, cover with fabrics, and let sit at room temperature until thick foam grows on top of it.
Remove the foam, sift the liquid, and pour it into clean bottles or cans (do not fill them too much).
Cover them tightly with lids or corks, place in a cold place for 12 hours.
After that, the kvass is ready.