Remove your prime rib from the refrigerator at least one hour before cooking time to allow the meat to reach room temperature.
If your butcher has not already done so, trim any thick pieces of solid fat from the roast, leaving the smaller areas of fat in place.
Preheat your oven to 450 degrees. Next dry the prime rib thoroughly with paper towels.
Using a sharp knife, make series of ½ inch deep incisions across the top of the roast as well as the sides.
Prepare your rub: In a medium bowl combine concentrated beef base with garlic. Using the mixture, generously cover all the exposed meat. Then, sprinkle the roast with thyme, oregano, black peppercorns, and salt. Place the roast into a roasting pan, bone-side down.
Place your prime rib roast in the preheated oven for 15 minutes, then reduce the temperature to 325 degrees. Roast until the meat has formed a brown crust and the instant-read thermometer inserted into the thickest part of the roast reads 130 degrees F (medium-rare.) This will take about 2 1/2 to 3 hours.
When the internal temperature of the roast reaches 130 degrees, take it out of the oven and cover with foil. Let the roast sit for thirty minutes before carving. Enjoy!
Allowing your prime rib to come to room temperature will ensure that your roast will cook evenly. When measuring the temperature of the prime rib, make sure that the tip of the insert-read thermometer is placed in the thickest part of the roast, not resting in fat or touching any bone for the most accurate reading.