Cut the tomatos into four pieces and put it in a broad vessel. Add five of cups of water. Add coriander seeds crushed coarsely and the ginger chopped finely to the tomato. Cook till the tomatos are soft. When it is cool, blend it in a blender and strain it.
Mix little water in the corn flour and make a thin batter and add to the tomato puree.
In a heavy bottomed vessel put the butter and add jeera and lightly fry. Add the tomato puree and boil in medium flame till it thickens. Add salt and pepper and garnish with croutons.