Pressurecook two potatoes.
Cool, peel and mash them.
Mix two cups of water, 1/2 tsp of turmeric powder and 1 1/2 tsp salt. Keep aside.
Potatoes should be mashed and a few pieces can be left as small pieces to provide texture to the dish.
Heat 2 tsp of any veg oil. Crackle in quick succession, 1 tsp mustard, 1 tsp urad dal and 1 tsp channa dal. When the dals are golden, put in 7-8 curry leaves, 1 inch piece of ginger sliced into thin strips, 3 green chillis slit lengthwise and 2 medium sized onions, sliced.
Saute well till onions are transparent (not brown). Pour in the potato mixture. Let it come to boil and then reduce the heat and simmer for five minutes till all are blended.
Garnish with fresh coriander leaves and serve hot with Dosas (for masala dosa) or with puris (for Puri-kizhangu).