One of the primary challenges with large whole muscle roasts, like a prime rib, is ending up with only a small overall portion of the meat cooked to the ideal doneness. The outside is often overcooked, and/or the center is often undercooked. In order to avoid or minimize this, I cook prime rib very gently at a low cooking temperature. Cooking sous-vide is a great approach. But you can still roast a prime rib in your oven with great results.
Low temperature cooking has its own set of tradeoffs though. The largest of these being that the maillard reaction isn’t achieved or is minimized. In order to still have a wonderfully browned crust while still roasting low and gentle, I like to sear the whole rib separately from the cooking process. I typically sear directly on a grill (as hot as possible), use a blowtorch, or a large cast iron griddle will do the trick too. Tip: skip the small butane torches you find at gourmet kitchen stores and get a larger propane torch at the hardware store - it will cost less and work a lot better.
You can mix and match your searing methods (grill, cast iron, torch, etc.) with your cooking method (sous vide, low temp oven, smoker, etc.). But as a general rule, if I’m cooking sous vide I like to sear after the cook. And if I’m cooking in an oven, I like to sear before.
With an understanding and plan of how you’re going to cook gently and sear separately, the recipe itself largely becomes only a formality. Nonetheless, my basic recipe can be found below. You’ll notice that it doesn’t rely on a long and fancy list of ingredients. And although low temp cooking is a relatively modern approach, it’s also pretty simple. Pick good ingredients, cook simply to let them shine, and it’s actually hard to not have a delicious result.
prime rib roast (bone-in preferred, and a for real treat go with a dry aged roast), with fat cap intact but trimmed of excessive fat
fresh minced garlic
fresh coarsely ground black pepper
Preheat oven to 240°F (for very large roasts, you may opt to go with a lower tempature)
Rub the outside of the roast with the brown sugar. Place roast on a roasting rack inside a roasting pan. Use a blowtorch to deeply brown all sides of the roast, creating a nice crust. Gently add the garlic, pepper and salt. You can be pretty liberal with the sugar, garlic, and pepper, but be more conservative with the salt.
Transfer to the oven and cook for ~1-2 hours, until the internal temperature reaches the mid to high 120°s F. Remove the roast from the oven, place on a wood board, loosely cover with foil and allow to rest for 20-30 minutes. The internal temperature should continue to rise during the resting period. Anything in the 131 to 139 F window will be a great medium rare. With practice and experience you’ll be able to narrow that target. I find that 135 to 136 F at service is my favorite.
To carve, separate the bones from the rest of the roast. Lay the bones on your serving platter or board. Cut the rest of the roast in half, perpendicular to where the bones were. Place each half cut side down and carve ~½ inch slices. Arrange on the platter and finish with a nice sprinkle of coarse sea salt. Serve with horseradish cream or your favorite accoutrements.