I cooked with kefir, I poured it on eggplant sauteed in a pan with some water, I used to use yogurt for a similar dish. And the liquid in the cooked dish seems stringy, sort of like okra in gumbo. However, the taste seems fine. What is happening? Did I do something wrong? How can I avoid the stringiness when cooking with kefir?
Sounds like it "broke", as can happen with any dairy product. The protein in the kefir coagulated into the strings you are seeing. If you decide to try it again, try the highest fat kefir you can find, minimize acid in the dish, and incorporate the kefir at a relatively low temperature.