Source: Dave Vaness (firstname.lastname@example.org), r.c.b., September 22, 1995
"For drink the peasant diet had kvas, which was much like the 'small
beer' of Western Europe. It could be made from grain and malt, but was
often made from leftover dark bread soaked in hot water and allowed to
ferment for a few hours; sugar, fruit or honey was customarily added as a
sweetener. The finished brew could be drunk on the spot or bottled for
later use; in some households a part of the brew served as a fermented
stock for soups. Homemade kvas is somewhat effervescent and only
slightly alcoholic. It has never enchanted many non-Russians, but it had
an important place in the peasant diet. It was cheap and the yeast
suspended in it, like the vegetables in shchi [cabbage soup] or borshch
(beet soup), formed a nutricious supplement to a limited diet."
Sprinkle the yeast and 1/4 teaspoon of the sugar over the 1/4 cup of lukewarm water and stir to dissolve the yeast completely. Set aside in a warm, draft-free spot (such as an unlighted oven) for about 10 minutes, or until the mixture almost doubles in volume. Stir the yeast mixture, the remaining sugar and the mint into the strained bread water, cover with a towel, and set aside for at least 8 hours.
Strain the mixture again through a fine sieve set over a large bowl or casserole, then prepare to bottle it. You will need 2 - 3 quart-sized bottles, or a gallon jug. Pour the liquid through a funnel 2/3 of the way up the sides of the bottle. Then divide the raisins among the bottles and cover the top of each bottle with plastic wrap, secured with a rubber band. Place in a cool -- but not cold -- spot for 3 - 5 days, or until the raisins have risen to the top and the sediment has sunk to the bottom. Carefully pour off the clear amber liquid and re-bottle it in the washed bottles. Refrigerate until ready to use. Although Russians drink kvas as a cold beverage, it may also be used as a cold-soup stock in okroshka (chilled vegetable soup with meat) or botvinia (green vegetable soup with fish).