This is a traditional bengali delicacy. This delicacy is rarely cooked nowadays. For this recipe, you need a fresh pumpkin leaves, which can only be found in your local fresh market, not in supermarkets. In simpler version, this dish can be cooked in a steamer without the leaf, too. Nowadays, this version is made more often than with leaves. But the addition of green pumpkin leaves with prawns marinated with mustard and coconut give it a splendid flavour.