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What do you do with leftover smoked prime rib? Make an out-of-this-world Prime Rib Steak Sandwich, filled with tender meat, melted cheese, and sweet caramelized onions, that’s what. Or go for our classic French Dip Sandwich with a homemade au jus. No matter which you select, your tastebuds will smile.
This is pretty much the greatest sandwich there ever was!
Table of Contents
For special occasions, we like to make any number of Prime Rib recipes. And whether smoked, Reverse Seared Prime Rib, or Grilled Prime Rib, it’s likely you may have some leftover. Enter the Prime Rib Steak Sandwich balanced with caramelized onions for sweetness and a mild and creamy horseradish sauce for flavor.
This is the BEST use for leftover Prime Rib (smoked or otherwise).
Ingredients + Substitutions
Below are some of the highlighted ingredients for our Prime Rib Steak Sandwich. The full and printable list is in the recipe card.
- Slices of Prime Rib – You can use any cut of beef roast you may have like smoked beef tenderloin or even a grilled picanha. or use the same portions with smoked ham. the key is thinly sliced.
- Bread – Our preferred bread is a baguette for the crusty exterior and soft insides. Or you can use ciabatta, or your favorite country loaf.
- Caramelized Onions – In addition to the horseradish sauce is perfectly caramelized onions to add a sweet bite and texture. We prefer red onions for added sweetness and bite, but you can use any onion you prefer.
- Horseradish Sauce – Add a bit of spice and fun flavor with a mix of fresh horseradish, sour cream, lemon and a few other fun ingredients.
How to Reheat Prime Rib
We like serving our steak sandwich with warm meat. Depending on how much steak you have, there are several options for warming up your meat. If you have about 2 pounds, like you see in the photo then you can take your roast and place it in the oven, set to 325 degrees Fahrenheit, for about 15 minutes or until warmed throughout.
You can use an instant read thermometer to avoid overcooking the meat. You don’t want to start cooking it again, you just want to warm it up. The length of time it will require to re-heat will depend on how much meat you have. Target an internal temperature of 135 degrees at the thickest part of the meat.
Optional: You can also just slice the cold meat and heat it up on the stove-top. You can also serve the meat cold. I won’t judge. But really, this prime rib steak sandwich is best made warm, with the ooey goodness of melted cheese smothering the warmed meat.
How to Caramelize Onions
While the meat is warming you can caramelize your onions. Just slice one red onion and cook it on the stove-top until slowly caramelized and sweet. This takes time for perfect caramelization and you can learn more in our article on how to caramelize onions. Roughly 30-40 minutes if you’re doing it right. But believe me, it’s worth every single minute for the sweet glory of perfectly caramelized onions.
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Steak Sandwich Horseradish Sauce
While all this is going on you can prep your creamy horseradish sauce. If you’re a traditionalist then it’s possible you used horseradish when you made your prime rib? Therefore it’s possible you have some leftover. If so you can just use that to make this creamy sauce which is perfect for any steak sandwich.
And for all you mayo-haters out there (I’m raising my hand high), this sauce is mayo-free. I want something creamy, but not too rich or oily. So I like sour cream as the base, then add in horseradish, chives and a few other ingredients for flavor.
Next all we need to do is assemble the steak sandwich.
How to Make the Best Leftover Prime Rib Steak Sandwich
To start I like a baguette for ease and crunch and for serving a group. And if you’re serving 4 or 5 people, it’s the perfect size.
- Portion the baguette into about 5-inch segments, and slice open lengthwise.
- Place a couple slices of provolone cheese on the bottom piece and place the bread and cheese under the broiler to melt.
- Once the cheese is melted (around 2 minutes), you can layer on your meat, arugula (or other crunchy greens), caramelized onions, and top with a generous drizzle of the horseradish cream sauce.
And you’ve got a winning leftover prime rib sandwich. Who knows, you may start smoking a prime rib just so you can use the tender slices to make these sandwiches? Just sayin.
Other Holiday Roast Leftover Ideas
Breakfast and Brunch Recipes
Smoked Ham Breakfast Hash – Perfect for leftover holiday ham
Recipe Roundups
16 Leftover Holiday Roast Recipe Ideas
Pizza Recipes
Leftover Turkey Pizza
BBQ Chicken Recipes
Smoked Buffalo Turkey Dip
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Prime Rib Steak Sandwiches
Ingredients
- 1 ½ lbs leftover prime rib, or other steak (about 4-6 oz per person)
- 1 white onion, sliced
- 8 slices provolone cheese
- 2 cups arugula, (or other crunchy green, lightly packed)
- 1 large baguette
For the Horseradish Cream Sauce
- ¾ cup sour cream
- 3 tablespoons horseradish
- 1 tablespoon Dijon mustard
- 2 tablespoons fresh squeezed lemon juice
- 1 tablespoon white wine vinegar
- ½ teaspoon kosher salt
- 2 tablespoon fresh chives, finely chopped
Instructions
For the Prime Rib Sandwiches:
- Preheat Oven: to 325 degrees.
- Make the Caramelized Onions: Heat a large pan on the stovetop to medium heat then add 2 tablespoons olive oil and the sliced onions. Stir occasionally until the onions are soft, golden/starting to brown, and sweet to the taste (roughly 30-40 minutes). Remove from heat. *You may need to adjust the heat and turn it down if they are browning too fast.
- Reheat Prime Rib: Place the leftover prime rib in a large cast iron (or oven proof) pan and place in the oven to heat up (approx 15 – 20 minutes). Remove from oven and slice into thin slices.
- Build Sandwiches: Cut the baguette into 4 equal-size pieces and cut them in half lengthwise. Place on a baking sheet, open-faced, and place two pieces of cheese on the bottom half of each sandwich. Place under the broiler for a couple of minutes to melt the cheese (paying close attention to not burn the bread).
- Once the cheese is melted, remove from the oven and build each sandwich: add 3-4 slices of the warm steak, a small handful of arugula, and a couple tablespoons of caramelized onions, then top with 1-2 tablespoons of creamy horseradish sauce. Serve immediately and enjoy the heck out of these epic sandwiches.
For the Horseradish Cream Sauce
- Place all ingredients in a bowl and mix together.
Notes
Nutrition
Nutrition information is automatically calculated, so should only be used as an approximation.
I didn’t follow the recipe exactly, but it turned out ahhmazingly delicious! Caramelized red onions a must and the horseradish cream sauce is divine! Will definitely have to repeat this one soon!
Delicious sandwich and the horseradish cream sauce is the best ever.
The sauce makes it- best prime rib leftovers we ever had.
This was the perfect recipe for our leftover ribeye roast. It was delicious and hit the spot. All of my children finished their sandwich and asked for seconds. The horseradish sauce was beyond and just scrumdiddlyumptious.
Love this! Thanks so much for dropping a comment.
This was fantastic!!