One teaspoonful of chopped parsley. Two tablespoonfuls of thick white sauce.
Wash the potatoes well, and scrape off the skins; lay them in cold water; next put them in a saucepan of boiling water, with two or three sprigs of mint and a teaspoonful of salt to each quart of water. Boil them until they are tender, then drain off the water; next dry the potatoes well in a clean cloth, put them in a hot vegetable-dish, and keep them hot.
Melt the butter in a saucepan, add the white sauce, stir it over the fire until it is hot, then strain in the lemon - juice, and add salt and pepper to taste. Beat up the yolk, stir it into the sauce, and stir the sauce over the fire to reheat it and cook the egg, but do not let it boil. Pour the sauce over the potatoes, sprinkle over the chopped parsley, and serve at once.
Cost from 6d., according to time of year.