Take a pint and a half or a quart of periwinkles, wash them well, and boil them in a saucepan with a handful or two of salt, to enable you to pick out the fish easily. Put a little dripping or butter into a saucepan, with an onion or carrot, some chopped parsley, and a sprig of thyme, and fry until it becomes brown. Add a pint of water to this, and as soon as it boils put in the periwinkles (which have been previously picked out of their shells), with a little pepper and salt, and let the whole boil again for half an hour.
It is only necessary to put them into a stew-pan with as much water as will prevent the bottom from burning, as the liquor oozing from them will be sufficient for the purpose; when the shells open wide enough to extract the fish, they will be sufficiently done.†
It is necessary to throw into the stew-pan a handful or two of salt with the periwinkles, otherwise half the fish could not be picked out. The "opening of the shell," refers, we conclude, to the falling out of the operculum.*
* 'British Conchology,' vol. iv. p. 252. † Murray's 'Modern Cookery Book'.