Take oil in a pan and add mustard seeds and cumin seeds. Let it splutter.
Add onions and let it turn golden brown
Add salt to taste
Add ginger garlic paste
Add the potatoes and mix well. Cover it with lid for 5 minutes
Add haldi, mirch powder and close lid again till oil separates and potatoes are cooked.
Add water and let it boil.
5 minutes lates cloae the gas. Add coroander and serve hot with chappati or white rice