Nothing goes together quite like a juicy prime rib and flavorful au jus. When you cook a prime rib in a roasting pan, you have an automatic head start on creating a thin but deeply flavored sauce for the meat, namely an au jus. With a name derived from the French phrase meaning "with juice," the sauce takes minutes to make but tastes like a lot of effort went into creating it. And while different recipes may use slightly different ingredients, there is a basic method for how to make an au jus for prime rib.
At its most basic, an au jus consists of deglazing the roasting pan with wine and broth, but other flavorings are often added, too. The good news about making an au jus is that it’s easy and quick. So, while your roast rests, you can whip it up.
What's the Difference Between Au Jus and Gravy?
Both gravy and au jus (try saying it like “aww zhoo”) start with the flavorful drippings left in the roasting pan after cooking a roast. However, a gravy is thickened with flour or cornstarch while an au jus is most often not. If you have ever had a French dip sandwich, that sauce on the side is au jus. You might notice that it's more similar to beef stock than gravy since you are starting with cooked, not raw ingredients.
Which Roasts Are Good For Making Au Jus?
Traditional au jus is made from beef drippings (though a similar light sauce could be made from a roast lamb or even chicken or turkey). Whatever beef cut you roast can yield the start of an au jus, but it’s most popularly served with prime rib (aka standing rib roast). An au jus adds moisture and flavor to the beef slices but still allows the meat to be the star.
How To Make Au Jus For Prime Rib
While you can certainly cook a beef roast directly on your Traeger grill grates, you will need to cook the meat in a roasting pan or over a rimmed baking sheet if you want an au jus. That’s because, as mentioned, the sauce starts with the deeply flavored pan drippings or juices.
Start by transferring the roast itself to a cutting board and reserving the pan drippings. If you are lucky, you will have ample juices/dripping in the pan (some roasts are even cooked with some broth in the bottom of the pan as well). Some of the juices may be liquid and some may be solid and stuck to the bottom of the pan. (Those stuck-on juices are the really tasty bits since they have browned.) If you see there is a lot of liquid fat on top of the juice, pour it off being careful not to pour off the juice. (Alternatively, you can pour the juice into a fat separator and then pour just the juice back into the pan.)
Add more flavor with aromatics. You will be heating the drippings in the roasting pan over a couple of burners on the stove and adding ingredients to it to make the jus. Though adding aromatic vegetables to the jus is optional, it boosts its flavor. The chopped trio of onion, celery, and carrot known as mirepoix (“meer-pwah”) is a great place to start. How much to use can vary but a couple of small carrots, a couple of stalks of celery, and one onion will likely do the trick. You want to chop these to get the most flavor, but since you will be straining the vegetables out, it can be a coarse and careless chop.
Beyond the mirepoix, consider adding some garlic and herbs like bay leaf and fresh thyme. (And, of course, a sprinkling of Traeger Prime Rib Rub would also be delicious.) Add all of these to the pan and cook over medium-high heat, stirring and scraping up the browned bits on the bottom of the pan, until the vegetables begin to brown (but not burn). If it seems the juices are in danger of burning, add a little water or broth to the pan.
Deglaze with wine or broth or both. Adding wine to the sauce adds complexity and helps carry flavors, but you can just add broth. If using wine, choose a dry red wine (not an expensive one, but one you would actually drink). Add about 1 cup to the pan and then let most of it boil off. After that, add good quality beef stock, between 1 and 3 cups depending on the size of your roast and the number of people you’re feeding. A splash of Worcestershire sauce will add even more savory flavor.
Simmer, strain, and season. Simmer the sauce for at least 10 minutes to meld and concentrate its flavors. Strain it, season it to taste with salt and pepper, and serve alongside the sliced meat.
Prime Rib With Au Jus Recipes
Now that you know the basics of how to make a prime rib au jus, you can make your own whenever you make a roast beef. However, there are also a handful of prime rib recipes on the Traeger site that have specific directions for an au jus. These include this delicious mayonnaise coated prime rib as well as this garlic crusted one.
Explore our other prime rib recipes for some inspiration:
How To Store Leftover Au Jus
If there’s any au jus left after the meal is served, hang on to it. If you are reheating leftover slices of meat, add some of the jus to keep them moist. You can also use the jus to serve with leftover prime rib to make a French Dip. Not only will this boost the flavor of a meat sauce but it would be delicious added to a risotto. It will keep, covered and refrigerated, for 3 days or frozen airtight for up to 3 months.