Question: how to cook gfs prime rib?
Answer: Preheat oven to 250 degrees F.
Remove product from bag.
Place roast on a wire rack inside the roasting pan and add 1/4″ of water to bottom of pan and cook uncovered. ... 
Cook For 2 1/2 – 3 hours or until roast reaches an internal temperature of 120 degrees F (Rare).