Prime Rib Roast: The Slow-Roast Method

By Danilo Alfaro

Updated 06/11/19

Prime Rib Roast
The Spruce
  • Total: 21 hrs
  • Prep: 16 hrs
  • Cook: 5 hrs
  • Yield: 1 Prime Rib (4 to 8 servings)
Nutritional Guidelines (per serving)
8 Calories
0g Fat
0g Carbs
1g Protein
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Nutrition Facts
Servings: 1 Prime Rib (4 to 8 servings)
Amount per serving
Calories 8
% Daily Value*
Total Fat 0g 0%
Saturated Fat 0g 1%
Cholesterol 3mg 1%
Sodium 40mg 2%
Total Carbohydrate 0g 0%
Dietary Fiber 0g 0%
Protein 1g
Calcium 1mg 0%
*The % Daily Value (DV) tells you how much a nutrient in a food serving contributes to a daily diet. 2,000 calories a day is used for general nutrition advice.
(Nutrition information is calculated using an ingredient database and should be considered an estimate.)

Prime rib is a large piece of meat, but just because it's big doesn't mean you can treat it roughly. It's big, yes, but it's from the beef rib primal, so it's also tender. As with anything tender, it's best to be gentle with it. 

To a tender rib roast, a hot oven acts like a hand squeezing water out of a sponge. Only instead of springing back like a sponge, ​the meat stays squeezed. The result: a dry, shrunken roast.

That's why the best way to avoid mistakes when cooking prime rib is to roast it gently. A low temperature doesn't squeeze, so there's little to no shrinkage, and the juices stay in the meat. The result: juicy, prime rib perfection.

The only catch is that the oven doesn't get hot enough to brown the exterior. We have to do that ourselves, directly in the roasting pan, across two burners on the stovetop. So make sure you have a heavy-bottomed roasting pan that's suitable for the stovetop.

This technique will work equally well for either a bone-in or boneless rib of beef of between five and 10 pounds. For a bone-in prime rib, figure two servings per rib, while a boneless roast will yield two servings per pound.

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Ingredients

  • 1 boneless or bone-in beef rib roast (trimmed and tied)
  • Kosher salt (to taste)
  • Freshly ground black pepper (to taste)

Steps to Make It

  1. Gather the ingredients.

    Prime Rib Roast ingredients
     The Spruce

  2. Pre-heat your oven to 200 F.

  3. Set your roasting pan across two burners on your stovetop. Add a couple of tablespoons of high-heat refined canola oil and get it smoking hot.

    Oiled roasting pan
     The Spruce

  4. Then add the roast and carefully sear it on all sides. Use tongs for turning it rather than anything that pierces it like a fork. Sear it for a total of 7 to 8 minutes until it's nice and brown all over.

    Prime rib roast on oil on pan
     The Spruce

  5. Season the roast generously with Kosher salt and freshly ground black pepper. For a boneless prime rib, put a roasting rack in the pan and then set the roast on it fat-side-up. With a bone-in prime rib, you can skip the roasting rack and set the roast bone-side-down in the roasting pan.

     The Spruce

  6. Insert a digital probe thermometer into the deepest part of the meat, being careful not to hit bone. Set the temperature alert to beep when the meat hits 128 F (see note below).

  7. Roast until the temperature reaches 128 F, which will be another 2 1/2 to 5 hours, depending on the size of your roast.

    Prime rib roast with thermometer
     The Spruce

  8. Remove from the oven and transfer to a cutting board and cover it with foil. Leave the thermometer in!

    Roast wrapped in foil
     The Spruce

  9. Once you take it out, the temperature should nudge up to 130 F, which is perfect medium-rare, and within 20 minutes or so it will drop back down to 120 F, which is when it's fully rested and ready to slice and serve.

    Prime Rib Roast
     The Spruce

  10. Serve and enjoy!

    Tips

    • The night before you're going to roast, unwrap the meat and let it sit in the refrigerator, uncovered, on the ​sheet pan with a rack. This will allow some of the surface moisture to evaporate, making it easier to get a beautiful brown crust when you sear it.
    • Three hours before you're going to roast it, take the meat out and set it on a sheet pan (to catch any juices) at room temperature. This step is important. If the meat is ice cold, the technique won't work as well. (And you don't have to worry about the meat going bad. Any surface bacteria are going to get seared immediately.)
    • Another advantage of slow roasting is that there's not much carryover cooking, so you don't need to rest the roast for very long. 
    • For medium-rare prime rib, we want to take the roast out of the oven at 128 F, and it will continue cooking until it reaches 130 F. If you prefer a medium prime rib, take it out at 135 F with a target temperature of around 140 F. Either way, you'll still want to rest the meat until it comes back down to 120 F before carving it.
    • Here's a simple au jus recipe you can make while the meat is resting. Or try this creamy horseradish sauce.