In a kadhai, add the olive oil and let it heat for a couple of minutes. Add the sliced onions and fry them until brown. Now add chopped ginger, garlic and green chili. Saute for a couple of minutes and then add the tomato puree. Mix it well and let it cool down a bit. Blend it in the blender (I used the fried onions instead along with garlic, ginger, green chili and tomato puree.)

Saute the mixture in the same kadhai for a good few mins. Add salt, turmeric, red chili powder, and garam masala. Now add the chicken pieces and mix it. Saute it for a good few mins covered. Uncover and let it roast for additional few minutes. Now add sour cream to it and mix well.

Saute additional few mins until the oil has been separated. At this point add water and cover it. Let it boil along with chicken for a few minutes. Now add kasoori methi and cilantro.

Your chicken curry is ready to be served. Serve it hot along with rice and chapati.