Prime Rib Sandwich (Use Any Leftover Roast Beef)

Close up of a prime rib sandwich on a black cutting board surrounded by au jus and beer.

Use your leftover Prime Rib to make a prime rib sandwich, featuring our delectable prime rib recipes, thinly sliced and piled onto crusty garlic bread, along with rich caramelized onions, melted cheese, salty prime rib au jus and, for those who like a little kick, pickled peppers (or pickled banana peppers).

This is a close re-creation of the famous shaved ribeye sandwich served at RH Rooftop. Houston’s Famous French Dip Au Jus has nothing on this bad boy!

Prime Rib Sandwich Recipe

While this sandwich recipe is titled “Prime Rib Sandwich” you can, in fact, use almost any other kind of roast beef. Think Picanha, Coulotte Steak, Sous Vide Ribeye, Sous Vide Tri Tip, Instant Pot Roast Beef, Smoked Beef Tenderloin, or sirloins.

We also offer up 3 different ways to cook your prime rib roast, if you’re in need of a new recipe: Classic Garlic Oven-roasted Prime Rib, Sous Vide Prime Rib and Smoked Prime Rib

How To Make

The longest step in making this sandwich is caramelizing the onions. Start those bad boys first, so they’re cooking while you’re working on the other elements. Next, whip up a batch of Prime Rib Sandwich Au Jus so it’s already ready to go when you remove the sando from the oven. When the onions are done it’s time to toast the garlic bread and build your sandwich! It’s a very easy sandwich to make, it’s just 10 minutes longer than most due to the onions.

Prime Rib Sandwich Ingredients - leftover prime rib, bread, au jus, onions, garlic butter, peppers and cheese.

How Do You Re-heat Prime Rib For Sandwiches

That’s the genius of this recipe…the leftover prime rib is only broiled for a few minutes, along with the rest of the sandwich, so it won’t overcook. Plus the au jus is served hot which will further “warm” the meat. No dry meat in this recipe! Your “pink center” will stay pink! It’s also how we make our Tri Tip Sandwich.

If you need tips to reheat large slices or a prime rib roast, reference our How To Reheat Prime Rib guide.

Slicing The Beef

For this shaved prime rib sandwich you want to slice the prime rib as thinly as possible. Not only will it take on a “melt in your mouth” texture but the meat will warm up quickly, removing the chance to overcook when re-heating. If you have a meat slicer, this is the perfect opportunity to whip it out. If not, grab your sharpened chef’s knife and carefully slice away. You can always put the meat in the freezer for 20 minutes to firm it up a bit before slicing. 

Side by side photos showing how to make a prime rib sandwich. The left shows two slices of toasted garlic bread, one with prime rib on it. The right photo shows two slices of toasted garlic bread, one has prime rib and caramelized onion on it.
Side by side photos showing how to make a prime rib sandwich. The left shows two slices of toasted garlic bread, one with prime rib, onions and pickled peppers on it.. The right photo shows two slices of toasted garlic bread, one is covered in two slices of cheese.

Best Bread To Use

Store bought garlic bread (either in a large loaf or individual slices) would work really well in this recipe. They tend to be loaded with garlic flavor and it saves you the step of making the garlic spread. If you are making your own garlic bread (we included our quick recipe for it!) we recommend using ciabatta bread, french bread or even a french baguette. All of these options toast well and love to be dipped in au jus.  

Roast Beef Sandwich with Horseradish Sauce

We get it. Prime Rib and Horseradish go together like cheese and crackers. So if you must add some horseradish, feel free to add in some Horseradish Sauce for Prime Rib, Horseradish Aioli or Horseradish Mustard. I promise you won’t miss it, however. The garlic bread and au jus provides ample flavor so a classic “prime rib sandwich sauce” isn’t needed. 

Don’t have horseradish? Here are some ideas to use as a horseradish substitute, in addition we have an informative article on prepared horseradish vs horseradish sauce.

Up close shot of sliced sous vide prime rib, on a black cutting board, with a side of au jus in a white glass cup.

How Long Are Roast Beef Leftovers Good For?

Per the USDA, leftover beef is best when eaten within two or three days. The more “well done” the prime rib, the longer it will last in the refrigerator.

Download our free Temperature Chart For Prime Rib Printable for the various temperatures as well as our How To Reheat Prime Rib guide.

Side Dish Ideas

This is pretty much a meal in itself, but if you’re looking for a side dish, we’d go with Air Fried Frozen French Fries, Air Fryer Baby Potatoes, garlic mashed potatoes, Ensalada de Coditos or Ensalada de Papa. Sous Vide corn on the cob would also work.

Close up of a prime rib sandwich on a black cutting board surrounded by au jus and beer.

What Else Can You Make With Leftover Beef

Instant Pot Bone Broth
Sancocho Dominicano
Philly Cheesesteak Sandwich
Roast Beef Sandwich with Horseradish Sauce For Beef Tenderloin
Instant Pot Beef Stroganoff
Steak and Ale Pie
Breakfast Skillet (Replace the sausage with beef)

What Wine Pairs With Roast Beef?

Bordeaux, Cabernet Sauvignon, Merlot, Shiraz, Malbec. Of course a classic Amber Ale beer would be stellar. 

Close up of a prime rib sandwich on a black cutting board surrounded by au jus and beer.

Prime Rib Sandwich (Use Any Leftover Roast Beef)

Delicious prime rib sandwich using leftover Prime Rib Roast. You can use any leftover roast beef you have on hand.
5 from 4 votes
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Prep Time: 10 minutes
Cook Time: 25 minutes
Total Time: 35 minutes
Servings: 1 people
Calories: 1488kcal
Author: Darcey Olson
Cost: $5



  • 1 Small Onion, Sliced
  • 1 tbsp Unsalted Butter ((*Note 2))
  • 1 tbsp Olive Oil


  • 2 Slices French or Italian Bread
  • 2 tbsp Unsalted Butter
  • 2 Cloves Fresh Garlic, Grated
  • Salt, To Taste ((*Note 3))


  • 2 Slices Provolone or Swiss Cheese




  • Cut the onions into strips, uniform in size.
  • Add the butter and olive oil to a large skillet and heat over medium high heat.
  • Once the butter is sizzling add the onions and stir to combine.
  • Turn down the heat to medium and let the onions sit, uninterrupted, for about 5 minutes.
  • Repeat for about 20 minutes. If needed, add an additional tablespoon of butter or olive oil. If you see the onions are starting to burn, turn down the heat to medium low. Continue to stir every 5 minutes until you're left with golden caramelized onions.


  • While the onions are caramelizing, now is a good time to start the au jus, if making from scratch. If re-heating left over Au Jus, now is a good time to re-heat it and let is simmer until the sandwich is finished.


  • Once the onions and au jus are cooking, proceed to making the garlic bread. Pre-heat the oven to broil (High).
  • Add butter and grated garlic to a small bowl and stir to combine.
  • Slather equally on the 2 slices of bread. Set aside until ready to cook and assemble.


  • Place the 2 slices of bread, garlic spread side up on a cookie sheet and broil for approximately 3-4 minutes, until your desired brownness is achieved. Remove from oven.
  • Set aside one slice of bread. Top the second slice of bread with the leftover prime rib, caramelized onions and pickled peppers and broil for 3-4 minutes, until the meat is warm. Add the cheese to the top and broil, in the oven, for approx. 1-2 minutes, until melted. Keep your eyes on the cheese – it will melt quickly.
  • Remove from the oven and immediately top the sandwiches with the top slice of bread. Serve with the warmed au jus and enjoy immediately.


Note 1 – You can sub in any sliced beef for the prime rib. 
Note 2 – You can use salted butter, if that’s what you have. 
Note 3 – You may or may not need extra salt. It depends how salty the beef is that you’re using. I recommend waiting until the entire sandwich is pulled together, taste, and salt as needed.
Note 4 – You can use any type of pickled peppers. Both pickled banana peppers and pickled jalapeno peppers work great.
Note 5 – Feel free to use store bought au jus if you prefer to keep it easy.
Note 6 – We added arugula to the sandwich since we had some to use up. The sandwich is perfect without it. 
The nutritional calculations do not include any added salt, au jus or pickled peppers. 


Calories: 1488kcal | Carbohydrates: 85g | Protein: 50g | Fat: 106g | Saturated Fat: 50g | Polyunsaturated Fat: 6g | Monounsaturated Fat: 42g | Trans Fat: 1g | Cholesterol: 219mg | Sodium: 1076mg | Potassium: 787mg | Fiber: 5g | Sugar: 8g | Vitamin A: 1387IU | Vitamin C: 10mg | Calcium: 403mg | Iron: 8mg
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