Take out extra oil from skillet leaving only 3 tbs. (this extra oil will be used later)
In this oil on low flame, add dry whole spices (green cardamom, black cardamom, cumin, bay leaf, cinnamon, pepper and clove), fry lightly to release flavors.
Now, add powdered spices (coriander and turmeric ), stir a little and add green masala and salt, fry for 1 minute.
Add chicken and fry till the color of chicken changes, add chopped or pureed tomatoes, cover and cook for 5 minutes.
After five minutes, add fried, crushed onions, cover and cook for 15 minutes till chicken is tender.
Add yogurt and plum, let simmer to reduce water. The gravy will be thick but not fully dried.
Add fried potatoes, chilies and coriander.