Everyone is chasing a restaurant quality prime rib and this technique ensures that you get one. Cooking slow and low then roasting allows you to use the oven for other dishes.
Technique tip: Air dry your rib roast for up to 3 or more days in fridge. This will concentrate the flavors by evaporating moisture from the roast similar to dry aging. This also creates an amazing crust when roasting. You can use this technique for roast chicken as well.
Swap option: Season a fresh raw roast or swap to cooked roast.
For the roast:1.
Line a half sheet pan with parchment paper, place a wire rack on top and place the prime rib on the rack.2.
Pat the prime rib dry with paper towels. Season the roast generously with salt, pepper and thyme.3.
Refrigerate the roast, uncovered, for one to two days before you cook it. This will give it a crispy, dark brown crust.
For the Horseradish Cream Sauce:
Place all the ingredients in a medium size mixing bowl and whisk until the mixture is smooth and creamy.
Place in the refrigerator for at least 4 hours or overnight to allow the flavors to meld. The sauce can be stored in the refrigerator in an airtight container for 2 to 3 weeks.
To finish the roast:1.
Preheat the oven to 250°F.2.
When ready to cook the prime rib roast, remove it from the fridge (no need to bring the roast to room temperature).3.
Cook the roast for 2½ to 3 hours, until it reaches your desired doneness and temperature. For rare, cook to 125 to 130°F. Medium-rare is 130 to 135°F. Medium-well is 135 to 140°F.4.
Pull the rib roast out of the oven and tent it with foil. The prime rib can rest for 30 minutes up to 2 hours. When your guests are ready to eat, raise the temperature of the oven to 500°F and roast the meat until you get a golden brown crust, 20 to 30 minutes. Another benefit of the reverse sear is you won't need to rest the meat again. Carve away.