Nearly all prawns sold in Britain, whether shell-on or peeled, are imported ready-cooked; they are sold widely, fresh or in frozen packs. Always allow a reasonable defrosting time; never defrost quickly in water. The best method is to sprinkle the prawns lightly with salt and then to defrost them on a plate overnight in a refrigerator.
Both shell-on and peeled prawns are used in a great many recipes for cooked and cold dishes, and garnishes.
These larger prawns come from various warm water fishing areas around the world. All supplies in Britain are frozen raw, headless, but with the shells. Packs of 1kg contain 16-20 prawns, depending on size. King prawns should be marinated before cooking, and their size and texture then make them well suited to grilling or barbecuing. If the prawns are wanted for a cold dish, poach in fish stock and allow to cool in the liquid. Chill king prawns well before serving.
Crystal prawns come from the Middle East or Far East fishing grounds. They are large whole prawns and sold ready-cooked; pink to orange in color. Defrost overnight in a refrigerator before cooking.