A Taste of Russia: Kvas

Kvas is the most popular drink in Russia, especially during the summer time. During the 19th century, peasants drank kvas very often, some say even more than water. Kvas is also known as "bread drink", but can also be added with fresh fruits and herbs during the spring time. It is usually made with rye, wheat, or malt flour that is boiled in water, then baked in an oven for 24 hours. Then the bread is dissolved in water for 2-3 hours and gets bottled. Kvas has a slightly alcoholic flavor, because of the way the bread is fermented, but the alcohol content is so small that children can drink it. Since the early 16th century, Russians have been drinking kvas for its unique sour taste and high vitamin B content. Today many street vendors sell kvas everywhere in Russia and if you can't buy it in Russia, you can have it shipped over to your home. If you want to try kvas, here is a website that sells it at a very cheap price:
http://www.russianfoods.com/showroom/product01422/vendor003E7/default.asp

Or you can try making it at home (good luck!):

Ingredients

1 lb stale black bread or 1 lb stale pumpernickel bread
1 cup sugar
2 tablespoons raisins
2 tablespoons fresh mint leaves or 1 tablespoon dried mint leaves
2 tablespoons Active dry yeast
1/4 cup luke warm water

Oven must be preheated to 200 degrees.

Cube the bread and then spread on a cookie sheet and place in oven for 1 hour.

Bring 6 quarts of water to a boil and drop in the bread.

Remove from heat, cover with a towel, and allow to sit at room temperature for 8 hours.

Strain through a fine sieve and press the juice from the bread.

Sprinkle the yeast and 1/4 teaspoon of sugar in the cup of lukewarm water and stir to dissolve the yeast completely.

Set aside in a warm place covered by a towel for approx. 10-12 minutes or until. mixture doubles in volume.

Add the mint leaves, and remaining sugar, stir well, then re-cover with the towel and set aside for 8-12 hours more at room temperature.

Again strain the mixture through a fine seive. Pour into a 1 gal. container, add the raisins, cover the top with plastic wrap, secure with a rubber band, and place in cool NOT cold, spot for 4-5 days or until the raisins are floating and the sediment has sunk to the bottom.

Pour off the clear amber liquid and rebottle in a clean jug or bottles. Refrigerate until ready to use.
You can enjoy kvas with a meat and vegetable dish or by itself.

sources:http://ask.metafilter.com/64513/Kvas-recipe,
http://www.traditional-russian-food.com/Kvas.html