Heat oil, mustard seeds. Add 4 cups water, tamcon, masala, turmeric, tomatoes, and salt to the pan. Boil for about 10 minutes. Add hing, rice powder and stir to thicken. Boil for another minute or so.
Masala: Fry all ingredients (except coconut) in as little oil as possible. Add coconut, grind (very fine) in blender.