I have been buying various spice mixes to make Pakistani/North Indian food myself. My issue is that in dishes with yoghurt and/or tomatoes, the end result always winds up being too sour. It happens with my karahis and also, most annoyingly, with channa masala.
I have tried various kinds of yoghurts, including plain low-fat yoghurt but also a Turkish one I found which had 10% fat. The result didn't change much. So, I don't think the type of yoghurt I am using is the problem.
Other than the acidity these dishes turn out alright. Which steps can I take to reduce the acidity of my dishes?
Update
I am restricting this question to chana masalas since that's what I have played around with the most. However, I am open for more general answers as well.
I usually put about half the amount of onion as tomatoes. Other than that, I usually follow the recipe on the box. The one I am currently using is this one.