Scrape nicely a large bunch of fine oyster-plant; plunge it into cold water containing two tablespoonfuls of vinegar, so as to prevent it from turning black. Take it from the water, drain, and cut it into two-inch-long pieces. Place them in a saucepan, with two tablespoonfuls of vinegar and two tablespoonfuls of flour; mix well; cover with plenty of cold water and a handful of salt; put the lid on, and let them boil slowly for forty minutes. Then drain, and return them to a sautoire, with an ounce and a half of the best butter procurable; season with half a pinch of pepper, the juice of half a lemon, and a tea-spoonful of chopped parsley. Heat well for five minutes, tossing occasionally; then place them in a hot, deep dish, and serve.