Kvas (or kvass) is a fermented drink made from rye bread that is popular in Russia. It's technically not alcoholic because the alcohol content is only one percent.The drink is bubbly but not as sweet as soda. Warning: this recipe needs to be prepared and fermented over-night!
Fill giant stock pot with 2.5 gallons of water (or divide it into two large pots) and bring to a boil.
While waiting, toast the bread slices twice on the darkest toaster setting. Darker bread makes darker kvass. Toast bread either outside or in your garage or your house will get smoky.
When water starts to boil, remove the pot from heat. Add a handful of raisins and toasted bread to the pot, cover with the lid and let it stay overnight or at least 8 hours.
Carefully remove toasted bread and discard it.
In a medium bowl, mix together 4 cups of sugar and 1.5 Tbsp of yeast, add them to kvas mixture and stir.
Cover with plastic wrap or lid and leave the mixture on the counter for another 6 hours, stirring every couple hours.
Discard floating raisins by scooping them up with a large spoon.
Using strainer or cheese cloth, pour kvass into bottles, close with a lid and leave them in the fridge overnight.