Apply salt to the prawns and set aside. Grind together the red kashmiri chillies, 1 pod of garlic, peppercorns, cumin seeds with vinegar.
In a pan heat the oil and put in the mustard seed and curry leaves. When it crackles add the onions and fry till they are transparent. Then add the chopped garlic, ginger and green chillies and fry for a little bit.
Put in the masala and the tumeric powder and mix. Add the prawns and coat all the prawns with the masala. Put in the vinegar. Cook till the prawns are fully done. When cooled can be stored in a glass jar.