Cut off the beet top and save for boiling or puree or gumbo. Soak the Beets in cold fresh water and wash well, taking off every particle of earth that may adhere. Wash them carefully, without scraping them. If the Beet is very tender, it will cook in an hour. Older Beets require all the way from three to four hours, according to size. If the Beet is wilted or tough, no amount of boiling will ever make it perfectly tender. If you break the skins of the Beets before cooking, the flavor will be lost, as well as the color, when boiled. Put the Beets into a pot of cold water, covering well, and boil until tender. Then set them to cool. When cold, slice nicely, and sprinkle with salt and pepper to taste and add vinegar, and set aside for an hour, for the vinegar to penetrate thoroughly. Serve as a salad.