Put the slIces of rye-bread in the oven (200 degrees Celsius) for about 45 mins, until they’re dried. Boil the 8 liters of Water. CRumble the dried rye-bread, put it in the boiling Water for about 5 mins. Let it the Water, and rye-bread rest for 4 hours, covered with a Tea-cloth. CRumble the yeast, 15 mins before the 4 hours are over. Mix the cRumbled yeast with some Sugar and the lukewarm Water. Let it rest for 15 mins. Filter the Water-rye-bread Mix in a kitchen sieve. Carefully extract all Water from the rye-bread. Wash, and peel the Lemon. Add the Lemon-peel, the Sugar, the yeast and the Mint. Stir the solution, and let it rest (covered) for 8 hours. Sieve the solution (Tea-cloth). Bottle it. Put some raisins, a bit of Lemon-peel, and a fresh leaf of Mint in every bottle, close the bottles, and keep them in a cool place. Ready when the raisins start floating. Sieve the stuff one more time in a Tea-cloth. Put the Kvas in the fridge 4 hours before drinking.