Remove the shells from the prawns and discard. Coat them lightly with the tumeric and salt. Chop the onions. Open the chilli to expose the seeds by slicing it down its length.

Put the oil into a large frying pan and heat untill hot but not quite smoking. Add the kalwanji which should fry instantly. Take the pan off the heat and add the prawns. Fry the prawns until lightly browned. Next add the onions and the green chilli. Cook on low heat with the lid on pan until the onions become soft and brown; the art is to be patient and let it all cook very slowly.

Serve.