Source: Atlas Obscura
Records of kvass date back as early as the 10th century. Thanks to its simple recipe and some help from Russian soldiers who brought it wherever they were stationed, this ever-so-slightly alcoholic, tangy beverage has become a staple throughout the Slavic nations.
To prepare kvass, brewers soak Russian brown bread or flour in water. They add yeast and optional flavoring, such as mint, honey, or berries, then ferment the mixture for a few days. The result is sour,…