Cutone whole chal kumro (ash gourd) into 3-4 segments- 3 to 3.5 inches. Then cut into rectangles or quarters and then you have to use a peeler to remove the skin and then shape the pieces so that there aren’t any sharp edges. After that, using a sharp knife, score the sides diagonally
Now add salt, ½ tsp of sugar and 1 tsp of turmeric powder to this. Rub it well and marinade and set aside for 15 mins.
Meanwhile make your mustard paste with 2-3 tbsp of black mustard seeds, salt, one green chili, and1 tbsp of mustard oil and use milk to grind instead of water. Once you have a smooth paste, strain this and set it aside.
In a frying pan or a flat-bottomed deep pan, heat 3 tbsp of mustard oil, add 2green chillies and ½ tsp of nigella seeds and then squeeze out excess liquid from each ash gourd pc and place in the pan.
Arrange them in such a way that each pc gets the heat. Keep the heat on medium and let one side brown and then flip and cook the other side.
Once you get a bit of colour, you can cover and let this cook. Keep the heat on low when you cover and cook.
When the chalkumro has become soft and has a nice colour to them, add the mustard paste and on low heat, add 1 cup of warm milk. Stir this, add salt and ½ tsp of sugar, 2-3 slit green chillies and then cover and let this cook till the milk thickens.
You can drizzle some extra mustard oil on this. Once thickened, take it out on a pan and serve with rice.