How can I keep yogurt from curdling...
when I am making curried chicken?
I saute the chicken, remove it. Saute onions and garlic, then add tomato sauce, then add yogurt, then spices. The yogurt almost invariably curdles. What am I doing wrong?
You need to add the yogurt gradually a couple of tablespoons at a time and saute until completely incorporated before adding more. It doesn't need to be cooked much after all the yogurt has been added, just a few minutes till it's all heated through.
Your problem probably stems from the fact that the yogurt is being cooked too long, as the order in which you are adding the ingredients is incorrect. The spices need to be sauteed with the onions and garlic before adding the tomato sauce and finally the yogurt.
I also have this problem every now and then. What helps is to lower the flame, add the yogurt last, after the spices, and turn the contents of the pan continuously after adding the yogurt. It also helps if you beat the yogurt with a fork beforehand. Some brands of yogurt are more prone to curdling than others. I use Trader Joe's "European Style Whole Milk". It's very good on its own too.
The yogurt should be up to room temp, and after the dish is finished, gradually "temper" (as you do with egg yolks) the yogurt with the hot finished sauce from the pan. Only then should the yogurt be stirred into the finished dish. So, start with warm yogurt in a bowl with room to add sauce, not just dumped in cold from the plastic carton.
Paula Wolfort has a method of stabilizing yoghurt in her Mediteranean Cooking book (I can't recall the exact title). It involves using cornstarch or eggs and heating it very slowly. I am sorry to be vague as I can't recall the details, but it seemed like a time intensive, but effective approach.