Grind ginger garlic with ¼ cup of water to thin paste and keep it aside.
Wash eggplants or baingan, take the cap out and slit them from both the sides. This way the spices will go very well inside the brinjal and give them perfect aroma and also help in cooking them faster.
Chop onion into thin slices and keep it aside. Heat oil in kadai or wok and add oil on medium heat and add sliced onions.
Saute couple of times and cook onions till the corners of onions become brown. Now add ½ cup of water to onions, cover with a lid, reduce the heat to medium low and cook till onion becomes translucent. It may take 5-6 minutes.
Once onion become soft and translucent add ground ginger garlic, dry spices, eggplants and ¼ cup of water.
Mix everything, cover and cook on medium low flame till eggplants become soft. Once eggplants are soft enough add tomato paste, slit green chilles and coriander leaves. If you still see onion pieces smash them with the ladle.
Cook in open for 4-5 minutes till gravy becomes little thick.