"Prime Rib Roast: The Traditional Method This prime rib roast is cooked using a very traditional method of roasting it on a high temperature for a few minutes and then reducing the heat and finishing the cooking at a lower temperature. This technique produces a perfectly medium-rare prime rib with a gorgeous brown crust on the outside. It will work equally well for either a bone-in or boneless prime rib of beef of between 4 and 18 pounds. For a bone-in prime rib, figure two servings per rib, while a boneless roast will yield two servings per pound. Also see: How to Roast Prime Rib..."