1. Place the roast in a roasting pan with the fatty side up. In a small bowl, mix together the garlic, olive oil, salt, pepper and thyme. Spread the mixture over the fatty layer of the roast, and let the roast sit out until it is at room temperature, no longer than 1 hour.
2. Preheat the oven to 500*F. (260 C).
3. Bake the roast for 20 minutes in the preheated oven, then reduce the temperature to 325*F. (165C), and continue roasting for an additional 60 to 75 minutes. The internal temperature of the roast should be at 135*F. (57C) for medium rare.
4. Allow the roast to rest for 10 or 15 minutes before carving so the meat can retain its juices.
Note: I chose to sear the meat then do cook the meat at the low temperature for a long time. It turned out great. Here is the information: Time and Temperature There are two ways you can roast it: At a low temperature for a long time, or At a high temperature for a shorter time. Your roast will shrink less if you cook it low and slow, but you won't get the same flavorful, well-browned exterior that a high roasting temperature gives you. It's possible to combine the two methods by starting the roast at a high temperature to sear the outside of it, then turning down the oven after 30 to 45 minutes to finish the roasting. If roasting at 325*F. (165*C), the meat will take about 17 to 20 minutes per pound. If you start the roast at 450*F. (235*C) for the first 30 minutes and then reduce the temperature to 325*F. (165*C), allow about 13 to 15 minutes per pound. The meat was tender and delicious.
I followed the directions exactly, only adjusting the time spent baking at 325*F. for my 7 1/2 pound prime rib. Because of the relatively low cooking temperature in the end, I waited until the roast temped at 135*F. before I pulled it out. After resting 20 minutes it was a perfect 145*F. I'm still reeling from how good this turned out -- better than ANY restaurant I've had it at! P.S. I was worried that cooking at 500*F. was burning that yummy crust created by the garlic and thyme, but I kept faith and stuck with it and it turned out nice and crispy, not burned at all.
**A Test I did was Wonderful! Even though I cooked a 4.5 lb roast, I made the amount of garlic mixture called for in the recipe, which covered the fat very generously and produced a delicious crust. One reviewer mentioned their garlic was bitter. I imagine that the high initial temperature of 500*F. scorched the garlic. I seared my roast at 460*F. for 12 minutes, and then since the fat seemed like it was on the verge of smoking, I turned the oven down to 400*F. for the last 8 minutes. I then roasted at 350*F. rather than the 325*F. in the recipe, until my meat thermometer read 130*F. It was juicy with beautiful pink color in the center. I did add some beef broth to the bits at the bottom of the pan and it made a lovely thick, rich, dark au jus. I would love to use this on other cuts of beef using the same method. Use an instant read thermometer and you cannot go wrong. I'm planning on using it again for our Christmas dinner.