1. Place the prawns in a wide, shallow dish.
2. Put all the ingredients for the paste mixture into a food processor and blend until you have a coarse puree.
3. Spoon this mixture over the prawns and toss to coat them evenly.
4. Make 4 squares of doubled-sided foil 30 cm square and divide the prawn mixture between them.
5. To seal the prawns in, make a parcel by bringing the edges of the foil together and crimping them together.
6. Lay the parcels on a baking sheet and place it in a preheated oven, 200 degree C, Gas Mark 6, and cook for 15-20 minutes or until the prawns have turned pink and are cooked through.
7. Remove the parcels from the oven, place each one on a plate and serve immediately, open the parcels at the table.