Clean, wash, peel and slice parwal and potatoes vertically. You can also scrape the skin of the parwal.
In a pressure cooker, heat mustard oil until smoky.
Reduce the heat to low.
Add nigella seeds, fennel seeds and allow it to crackle.
Add onions and fry until just golden brown. Do not burn them.
Add potatoes, parwal, green chili and sliced tomatoes.
Saute on high heat for 3 to 4 mins.
Add turmeric, achari masala, amchoor and mix.
Sprinkle some water, cover and cook until done.
Lastly, add salt, mix and cook for another minute.
Dish out and garnish with fresh coriander leaves.
Serve hot with pooris or phulkas of parathas of your choice.