This is an Uzbek version of a Russian soup. In Russia, the soup is made with Kvass (a national drink made with brewer's yeast and rye bread). In Uzbekistan, the soup is made with fermented mare's (horses) milk. I prefer to use a thinned plain yogurt. My husband, who is not adventurous, loves this soup in the summer and we have it often. The original recipe came from "Please to the Table - The Russian Cookbook" by Anya von Bremzen and John Welchman. I have modified it quite a bit so think I can almost, not quite, call it my own recipe. Prep time does not include chilling time.