Soak methi seeds in water and set aside for 3-4 hours.
Drain the water (keep aside for gravy) and grind the seeds coarsely using a mortar pestle.
Heat mustard oil in a heavy bottom pan. When the oil is hot, add heeng, zeera, methi seeds, saunf and dry red chilies. Sautee for a few minutes till fragant.
Add the roughly chopped potatoes and green chilies. Add all dry spices namely turmeric powder, kashmiri red chili powder and salt. Mix well
Add 4-5 cups of water and bring it to a boil. Let the curry simmer for 20-25 minutes. Add amchoor powder and mix well.
Switch off the gas, garnish with coriander leaves and serve with pooris or kachori