Coat the boiled duck eggs with salt, a little turmeric powder, and red chili powder.

Pour the mustard oil into the pan. Add the eggs to the hot oil and pan-fry them.

(Pro Tip: I keep the oil moderately hot because duck eggs can blister quickly if the heat is too high.)

Take them out and transfer them to a plate once lightly fried.

Add bay leaves, cumin seeds, cinnamon sticks, and green cardamom to the remaining oil in the pan.

When the whole spices start releasing their flavors, add chopped onions and fry them until golden brown.

(Pro Tip: I never rush this step. Properly golden onions give the kosha its authentic deeper look and flavor.)

Add tomatoes and a little bit of salt. Give them a good stir.

Once the tomatoes become soft, add ginger-garlic paste and stir well.

A thick paste will form. Add a little more turmeric powder, red chili powder, Kashmiri red chili powder, coriander powder, and cumin powder. Mix well.

Add a little bit of water and sauté the spices.

Then add more water according to desired gravy consistency.

(Pro Tip: I prefer adding water little by little here, which helps the spices cook evenly without losing their roasted character.)

After the water comes to a boil, add lightly fried boiled duck eggs and salt.

Once the gravy thickens, add roasted cumin powder and mix well.

Sprinkle coriander leaves and pour the Hasher Dim Kosha into a serving bowl.