Boneless Prime Rib with Au Jus

Roasting a prime rib can be a little a LOT intimidating.  It’s a pricey cut of meat (but so worth it) and the biggest mistake is overcooking it beyond medium rare.  The method I’m sharing results in a perfectly medium rare prime rib with a crispy, deep brown crust.

This recipe was originally published in 2018. I have updated it with new photos (including step-by-step photos).

My mama has always roasted a prime rib for our annual gathering every Christmas Eve. My recipe is based off of hers that she adapted from Allrecipes.  I’ve made a few changes to it over the years to put my own twist on it (but I still love Mama’s!).

This method uses a flavorful marinade that is injected into the roast, which brings out the flavor in the meat without being overpowering.  The drippings and marinade mixture help to make an incredible au jus that is prepared during the resting time of the roast. This prime rib is also delicious served with homemade horseradish sauce.

Let’s get started on how to roast the perfect boneless prime rib!

What You’ll Need

• Prime rib – This recipe is based on roasting a 6 pound roast.
• For the marinade that you’ll inject into the roast – Water, Worcestershire sauce, soy sauce, onion powder, garlic powder and browning sauce.
• For seasoning the roast – Olive oil, salt and pepper.
• For the au jus: Beef broth and flour. You’ll also need some of the pan drippings for the au jus.

What is Browning Sauce?

Browning sauce is a dark-colored sauce that adds depth of flavor (and color) to meats, soups, gravy and marinades. I like to use it my recipes if I can, but it’s not required in this recipe (you can substitute with extra Worcestershire sauce).

Browning sauce is typically found on the aisle in the grocery store that has packets of gravy mixes and jars of pre-made gravy.

Three Important Rules When Roasting a Prime Rib

• Allow to reach room temperature before roasting.
• Use a digital instant read thermometer. A leave-in thermometer is best for ensuring 100% temperature accuracy. I also use an instant read thermometer when the roast is removed from the oven.
• Allow to rest after roasting.

Calculating Number of Servings

I always use a boneless prime rib because it’s easier (for me) to calculate how many pounds I’m going to need for my guests.  A good rule of thumb is ¾ pound per person.  I’d rather have too much than not enough, so I personally calculate 1 pound per person.  I mostly always have leftovers, but am content in knowing there will be enough for everyone (and who doesn’t love leftover prime rib?!).

This method starts at a high temperature to brown the crust, then the heat is reduced to retain juiciness.  Since the roast will be removed at low temperature of 200 degrees F, you’ll need to remove it only 5 degrees before your desired temperature. 

For medium rare (130 to 135 degrees F) you will need to remove the prime rib at a temperature of 125 to 130 degrees F, then allow to rest covered loosely with foil until temperature reaches 130 to 135 degrees F.

How to Roast Boneless Prime Rib

Prepare the marinade by whisking together the marinade ingredients.

Using an injector, inject approximately ¾ cup of the marinade throughout the roast.

Pour the remaining marinade into the bottom of your roasting pan.

Season the roast by rubbing it with olive oil, then rubbing it with salt and pepper. Allow the roast to come to room temperature by letting it sit for 2 hours.

Once it has roasted completely (according to the directions in the recipe card) and is resting, you’ll prepare the au jus.

You’ll need ⅓ cup of pan drippings for the au jus. Sometimes I find that I don’t have enough drippings. This depends on the fat content in your roast and also if you are using a darker roasting pan.

What I do is add ½ cup of beef broth to the existing drippings.

Then I use a spatula to scrape up the drippings and mix with the beef broth (you can also use water).

Behold, we now have enough drippings to make the au jus!

Make the au jus by heating ⅓ cup of the drippings in a medium saucepan, then add flour to form a paste. Pour in beef broth, whisk to combine and gently boil for a few minutes until slightly thickened.

Prime Rib Temperatures

• Rare:  120-125 degrees F
• Medium Rare:  130-135 degrees F
• Medium:  135-140 degrees F
• Well Done:  145+ degrees F

Once your roast is ready to serve, why not garnish the platter for a festively beautiful presentation? I like to use fresh rosemary sprigs with pomegranate arils or fresh cranberries.

I hope you and your family enjoy this prime rib as much as we have over the years!