De-shell and clean the prawns carefully, keeping the heads and tails intact. Smear the prawns with a little turmeric and salt.

Heat 1 tbsp of mustard oil in a pressure cooker till smoking hot. Cool the oil. Add the prawns and fry till light golden (be careful not to over fry the prawns). Keep aside. (If your prawns are fresh enough, there is no need to fry them.)

Add another 2 tbsp of the oil to the same pressure cooker, sprinkle in the panch phoron and allow to splutter. Throw in the chopped onions, potatoes, tomatoes, green chilies, coriander leaves, the remaining turmeric powder and salt.

Cook for 2-3 minutes and add 2 cups of warm water. Bring to a simmer, add the fried prawns, sugar and adjust seasonings.

Cover and cook, 1 whistle, definitely no more than 2. Switch off the flame and allow to rest.

Garnish with chopped coriander leaves, a drizzle of mustard oil and serve hot with rice.