Once hot add mustard seeds. Let them pop and then add cumin seeds. Let them sizzle a bit.
Add dried red chili. Saute for 15-20 seconds.
Then add asafetida and turmeric powder.
Immediately add cubed potatoes. Mix it well.
Add coriander powder, cumin powder, red chili powder and salt. Mix it so all the potatoes coated with the masala.
Add 1 cup of water. Stir it.
Cover the pan and cook. Stir in between and make sure that there is enough water and potatoes are not sticking to the bottom of the pan. If needed add more water.
Cook till potatoes are tender.
Now mash very few potatoes with back of your spoon, so gravy will become thick.
Add jaggery and tamarind paste. Mix and cook for a minute.