1. Heat oil, then saute the onion, ginger and garlic for a few minutes.
2. Add all the dry spices, and fry some more.
3. Add chicken and let it cook for about 10 minutes or so. Keep stirring.
4. Whisk the dahi and tomato paste in a bowl.
5. Add the mixture to the chicken, then add the potatoes and water.
6. Bring to a boil and cover.
7. Reduce heat and simmer for 15 mins.
8. Stir occasionally.
9. Serve with steamed rice.

Image: Flickr/creativecommons terreninvirginia