Frozen prawns must be completely defrosted before they are placed on heat. Here is a 3 step method: 1. Transfer the contents of the pack into a polybag. 2. Poke some holes in the polybag for it to remain fresh. 3. Place the polybag in a container of water for 20 minutes. You will find all these instructions on the pack of bag also so that you can read them conveniently. Once prawns are thawed, they should be used as early as possible and they must not be place for re-freezing.