By diluting plain yogurt with water and adding salt, you have created ayran. It is a very simple and very delicious drink which is served ubiquitously throughout Turkey. Common with meat or pizza sort meals, ayran is not often offered with seafood because of some superstitious about a negative reaction occurring in your intestines.
Ayran machines can be seen continuously mixing the drink so it stays uniform in texture and foamy on top. This is called açik ayran whereas the sort sold in individual containers is called kapalı ayran.
Towards the East part of the country, ayran can be found with carbonation and sometimes with fresh thyme or mint leaves.