We have prime rib roast every year for christmas. It took a lot of either over or undercooked meat before I finally found a trick that works. All you do is set the meat out so that it's at room temperature when you cook it. You preheat your oven to either the lowest temperature it will go to or to the temperature that you'd like the meat to get to(check online for meat internal temperatures). For instance, we like our meat pretty rare so we use the lowest temperature which on our oven is 170. You can cook it as long as you want and the internal temperature of the meat will only go as high as the oven temperature. I usually put my meat on for about 6 hours at 170 degrees. It comes out super tender and delicous. Oh, and be sure and put the roast in with the fatty side up so it will drip down onto the meat and keep it juicy. I hope this helps.