Throw a handful of salt into a pot of boiling water. When it boils very hard, put in the prawns. Let them boil a quarter of an hour, and when you take them out lay them on a sieve to drain, and then wipe them on a dry cloth, and put them aside till quite cold.
Lay a handful of curled parsley in the middle of a dish. Put one prawn on the top of it, and lay the others, all round, as close as you can, with the tails outside. Garnish with parsley.
Eat them with salt, cayenne, sweet oil, mustard and vinegar, mixed together as for lobsters.
Crabs are boiled in the same manner, and in serving up may be arranged like prawns.