My relationship with this yogurt soup is a lot like that of John Cusack and Kate Beckinsale in the movie Serendipity (I'm Kate Beckinsale in this situation).
Before seeing a theater production one evening here in Ann Arbor, a group of friends and I were headed to a local Indian restaurant that was the talk of the town. Well, the town was too talkative about it, because the wait was two hours and we didn't have that kind of time. So, we went next door to a place I didn't even know existed, and it changed my life.
We ended up at a local Turkish restaurant, Ayse's Cafe, and their soup of the day was Yayla Çorbasi, a yogurt soup, flavored with mint and chili and thickened with rice and chickpeas. It was one of the best soups I've ever had and I've been thinking about it often since then.
I've attempted to look up recipes for it in the past, but didn't find anything that resembled what I had at Ayse's, so I never took the plunge and tried to make it — and then I decided to do soups month and thought it was the perfect time to do more research.
There aren't a ton of recipes for this soup on the Internet, and the few I did find on personal blogs looked either too thick, had too much added in addition to the basic rice, chickpea, yogurt combination I was looking for, or had broken emulsions where the fat from the yogurt didn't combine with the stock properly leading to a not very appetizing, grainy final look.
So, I went back to the books to find more traditional recipes, the end result here is a combination of what I read in books like Splendid Soups from James Peterson and Classic Turkish Cookery by Ghillie Basan and some of the more successful recipes I found on blogs. The final result will be a vibrant, slightly tart soup accented with a slight heat and herbaceous note from the chili oil and fried mint oil.
It's really good, you should try it!
It's important to not boil the soup after you add the yogurt, and if you are heating up leftovers, do so slowly so as not to break the soup or curdle the yogurt.