I mean me, not shorshe chingri. Just in case you didn't get it.
Mustard oil, no substitution.
White prawns (shrimps, in America), shelled and veined. NO pre-cooked nonsense, thank you.
Potatoes, peeled and sliced as shown in picture below.
Pumpkin (kumro), peeled and seeded. Sliced like potatoes.
Note: I don't use the pumpkin in the US because the supermarkets do not carry anything labelled 'pumpkins'. I am told 'squash' is an acceptable substitute (which is strange since I thought pumpkin was a kind of gourd), but since there are many different kinds of squash, I'd be grateful if someone let me know which one is closest in taste to the pumpkin.
Grind the mustard seeds into a granular paste with salt and a little water. It is vital to add the salt, because mustard seeds turn bitter when pasted. The salt, for some biochemic reason beyond me, prevent this. The paste can be made in a food processor, a ten-dollar coffee grinder (you can grind salt and mustard together and add water later) or by hand in a mortar-and-pestle. We also add a couple of green chilies to the paste, but it might be too hot for some.
The American variant:
When the paste is done, taste it to how salty it is. Now, in a large piece of aluminium foil, place prawns, potatoe and pumpkin slices. Pour mustard oil liberally over them. Now spoon in generous amounts of mustard paste and mix everything well with your hands. Don't be finicky, spoons and forks cannot do this job quarter as well. If the paste wasn't salty enough, add some salt. Add a little sugar. If you like your food with a small amount of heat, add a few sliced green chilies.
Wrap the aluminium foil into a tight pack. Put it on a baking tray. Pop it in a preheated oven. Broil at around 400F for twenty minutes. If cooking larger amounts, do it in a covered baking dish coated with mustard oil. Take out and check if potatoes and prawns are well done. A fork should be able to cut through a prawn like a warm knife through butter, not merely go in easily. If not, put it back for another 5-7 minutes. And that's it.
Baked prawns and potatoes. Served in a fish-shaped serving dish.
The Indian variant:
Grease a thich tawa with mustard oil. Arrange the prawns and vegetables, well mixed with mustard paste and oil and salt and sugar, on this tawa. Cover with another tawa, a suitable dish cover, anything that seals off all steam escape route. Now slow-cook over a low flame. Be sure to grease the tawa well, or the lower layer of prawns and potatoes will char. This can be pulled off in a cast-iron flat-bottomed saucepan, too. Don't use the teflon coated nonsense. They're too thin, and unless insanely expensive, tend to flake.