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 the chicken pieces, reduce the flame and sauté till the chicken starts cooking in its 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.