Kvass is a fermented beverage made from stale dark, sourdough rye bread. It's brown and bubbly, with a beer-like taste, but its alcohol content is so low that it's considered non-alcoholic. Kvass is a staple of Russia, enjoyed by czars to peasants. Kvass has properties that protect against infectious disease and even protect against cancer development. It's tangy and not too sweet flavor, and it's said to be among the best things on earth to quench your thirst.