In a saucepan, heat oil. Sauté onions till just wilted.
Add in the pound ginger and garlic and sauté till raw smell is gone.
Add the ground paste and cook till oil floats in the top.
Add the chicken, salt and the ground powder and mix well.
Cook covered till almost done, stirring occasionally.
Finally add the chopped tomatoes and cook for a couple of minutes.
Just before serving, squeeze in the lemon juice.