Wash potatoes under running water. Peel and dice them to 1 inch. Add them to a pressure cooker or regular pot and pour 1 cup water.
Pressure cook for 1 whistle on a medium flame, until soft and slightly mushy. If cooking in a pot, bring the water to a rolling boil on a high heat, reduce and cook until they are soft. If required add more boiling water.
While the potatoes cook, slice the onions, chop the tomatoes, ginger & green chilies,
Pour oil to a pan and heat it. Add cumin, mustard, chana dal and urad dal. Fry until the lentils turn golden and aromatic.
Stir in the curry leaves and green chilies. Fry till leaves turn crisp. Sprinkle hing.
Add onions and ginger. Saute them on a medium heat until they lose the raw flavor & turn pink.
Add tomatoes, turmeric and salt. Cook stirring often until the tomatoes turn mushy and the raw smell has gone completely.
Transfer the cooked potatoes along with the water (potato stock). Mash them slightly to make it a thick curry. If required pour some hot water to bring it to a consistency.
Taste test and add more salt and green chili if required.
Mix well. Cook covered for 3 to 4 minutes until the curry reaches a thick consistency.
Sprinkle coriander leaves. Serve poori masala with hot Pooris. If you want you may squeeze some lemon juice.
Pour oil to the steel insert of the Instant pot. Press the saute button. When the oil turns hot, add mustard, cumin, chana dal and urad dal.
Saute until lightly golden. Stir in curry leaves, ginger, green chilies & hing.
Add onions and saute for 2 to 3 mins until transparent. Add tomatoes, salt and turmeric.
Saute until the tomatoes lose their raw flavor for 2 to 3 mins. Press cancel.
Add potatoes and pour 1 cup water. Deglaze and pressure cook for 4 mins. Release the pressure immediately. Mash some of the potatoes to thicken the curry. (check pics in the post). Taste test and add more salt if required.
Poori masala is not a dry curry so it should be like a thick gravy consistency. If the consistency is too thick pour some hot water and mix well.
Sprinkle coriander leaves and lemon juice. Serve with Poori.