Take the leftover of sambhar and rasam and mix them and boil them for few minutes.
Take a pan and add mustard seeds, cumin seeds and ginger. When it splutters add onion, tomatoes, potatoes and any vegetable of your choice. Fry a little, pour it in the leftovers and boil it for few minutes.
When ready garnish with coriander leaves and serve hot with chapatti, roti or rice.