Cook the prawns along with turmeric, salt and vinegar.Try to cook in the pressure cooker. Make sure all the water is evaporated.
Once cooled , press the prawn with a stone or masher(make sure you dont powder it).
Take 1 cup of mustard oil or any oil and fry prawns.
Take all the leftovers of the prawn from the oil and mix it with the fried ones.
Add little more oil to the existing oil and fry baby onions , garlic cloves seperately and keep it aside.
In the oil add mustard seeds and when it cracks add Dried red chillies and all the above said mix and fry for 2 minutes.
Once cooled store it in a air tight jar.Make sure oil tops the mix when in jar.