Heat oil in a pan. Add the onion slices and half of the fresh ginger and garlic. Sauté well. Add the ginger-garlic paste, dry masala powders, vinegar, salt and coriander leaves. Add in the chicken pieces, reduce the flame and sauté till the chicken starts cooking in its own juices. Pour in half a cup of water, mix well, add the rest of the chopped ginger and garlic. Close with a lid and cook till the gravy thickens.