~Remove a thin slice from both ends of the onion ~quarter lengthwise ~place onions in an oiled baking dish/pan, ~brush with oil and salt lightly ~cover (with aluminum foil if dish does not have it's own) ~bake at 350 for 30 minutes, or until tender ~Remove cover, brush again with oil, sprinkle with vinegar bake 45 to 50 minutes longer, turning onions several times and basting with oil