In a pressure cooker, add all the ingredients, mix together and pressure cook upto 3 whistles. If cooking over stove top, cook till the potatoes are well cooked.
Heat oil in a pan and splutter mustard seeds.
Now add well cooked potato curry to the pan and let it boil for few minutes.Check the salt.
Cook on slow to medium flame without lid for 10 minutes or till you get the consistency of your choice.