The best prime rib sandwich is made with leftover roast prime rib, fresh crusty bread, zesty horseradish sauce, and sweet caramelized onions. It’s an easy sandwich to make with tons of mouth-watering flavor!
When you make a Prime Rib dinner for a holiday or for your family, you want to make sure that you eat every single bit of it. Prime Rib is expensive!
Don’t let your leftover prime rib go to waste! use it to make these amazing savory sandwiches.
If you like being able to make sandwich shop favorites in your own kitchen, you should check out my Philly Cheesecake recipe next. You’ll also enjoy making French Dip Sliders, Chicken Parm Sandwiches and Bagel Breakfast Sandwiches too.
Why You’ll Love This Recipe
- Perfect for Leftovers – I can’t decide if I like the freshly roasted prime rib dinner, or the second-day leftover prime rib sandwiches better!
- Traditional Flavors – Savory roasted beef pairs beautifully with tangy horseradish sauce and sweet caramelized onions.
- Versatile Recipe – Switch out the bread, add other toppings, or make this into a prime rib panini if you have a sandwich press!
Key Prime Rib Sandwich Ingredients
Here’s what you need to make the perfect sandwich with leftover roast prime rib.
Complete list of ingredients and amounts can be found in the recipe card below.
- Prime Rib: Ideally you saved some of your prime rib roast from last night. If it isn’t already sliced, slice it thinly for sandwiches, and remove any large pieces of fat.
- Onions: Slowly caramelized onions add a rich and delicious sweetness to the sandwiches.
- Arugula: This soft green has a bit of a peppery flavor and it’s delicious with beef. In the UK it’s called wild rocket.
- Horseradish Sauce: If you’ve made my prime rib I hope you also made the fresh horseradish sauce that goes with it! If not, I’ll share the recipe in the recipe card for you so that you can whip up a batch just for these sandwiches. It’s the best part – so flavorful and just a little bit spicy.
- Bread: I’m using a sourdough baguette cut into 4-inch pieces, but you could also use ciabatta rolls or any crusty bread that you enjoy.
How To Make A Prime Rib Sandwich with Caramelized Onions
- Cook Onions: Heat olive oil in a pan over medium heat, and add the sliced onions.
- Actively Cook: Cook the onions, stirring constantly. We want all of the surfaces of the onion slices to cook slowly to bring out the caramelization.
- Keep Cooking the Onions! It takes at least 20 minutes to properly caramelize onions, so continue cooking them until they are golden brown.
- Assemble the Sandwiches: Remove the ends of the baguette, slice it into pieces, and slice each piece in half lengthwise to open it up. Spread horseradish sauce on both sides, then layer the leftover prime rib, caramelized onions, and arugula into each sandwich. Finish with a sprinkling of ground black pepper and serve right away.
Tip!
You can make sandwiches with cold prime rib slices, or you can warm up the meat. Be sure to only warm the meat briefly in a frying pan, you don’t want it to cook any further or change color.
Recipe Tips
- You don’t have to use prime rib. This sandwich will be just as delicious made with any type of leftover roast beef!
- Plan Ahead. While you’re picking up the prime rib from the store, grab a baguette and some fresh arugula so you’ll be ready to make these sandwiches the next day.
- Slice Cold. Prime rib is much easier to slice thinly when it’s cold, rather than when it’s warm from the oven.
- Variations: Add thinly sliced tomatoes seasoned with salt and pepper, or make a hoagie-style prime rib sandwich by layering the meat with garlic mayo, tomato, lettuce, and provolone cheese.
- Other Greens: Use baby spinach, chopped romaine, or any other greens you enjoy in place of the arugula if you’d like.
How To Make Horseradish Sauce for Prime Rib Sandwiches
You can see this recipe for homemade horseradish sauce, or you can follow these quick instructions. The full recipe including ingredient amounts is in the recipe card below.
To Make Horseradish Sauce, combine sour cream, prepared horseradish, mayo, apple cider vinegar, Dijon mustard, chopped chives, salt, and pepper in a bowl.
Stir until combined, then cover and refrigerate until you’re ready to use it.
While you can use this sauce right away on your sandwiches, the flavors meld and intensify if you let it chill for a few hours, or better yet overnight.
Storing Tips
This sandwich is made with leftover prime rib, and it’s not ideal to have leftovers of leftovers! Make prime rib sandwiches when you’re ready to eat them.
If you have more prime rib leftovers to use, try making my creamy prime rib pasta with mushrooms recipe too.
What To Serve With Prime Rib Sandwiches
As with most sandwiches, this one is delicious with a side of french fries, a salad, or a cup of soup.
Fries: Homemade french fries are my favorite, but you can also make oven baked fries.
Salad: Try my tasty Beet Salad or an Italian Olive Garden Salad with your prime rib sandwiches.
Soup: If you have the time, make a batch of homemade soup to go with these sandwiches. A rich, creamy soup like cream of onion or cauliflower leek soup would work perfectly.
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FAQs
Leftover prime rib is delicious when it’s cold, and it’s especially delicious when made into these prime rib sandwiches. If you prefer the meat warmed up for sandwiches, just be sure to heat it up gently so that it doesn’t overcook.
The best way is to heat a pan over medium heat, and then add the sliced meat, one at a time. Cook very briefly on both sides, being careful not to let the meat change color.
A hearty, crusty bread makes the best prime rib sandwiches. You can use ciabatta, sourdough, or a rustic Italian loaf to make this recipe. Hard rolls work well too.
If properly stored, prime rib can be kept for about 5 days in the refrigerator. These sandwiches are best when you make them a day or two after you first cooked the roast.
Prime Rib is good, but these prime rib sandwiches made with the leftovers might be the best part! Save this recipe for the next time you have prime rib to eat – you’ll be glad you did.
Did you make this? Be sure to leave a review below and tag me on Facebook, Instagram, or Pinterest!
Prime Rib Sandwich
Ingredients
- 2 tablespoons olive oil
- 2 medium yellow or white onions thinly sliced
- 1 baguette
- ½ cup horseradish sauce Use leftovers from your prime rib dinner or follow the recipe included below
- 1 pound cooked prime rib sliced thinly and fat trimmed
- 2 cups arugula wild rocket in the UK, or any other greens
Horseradish sauce
- ¼ cup sour cream
- 1 tablespoons prepared horseradish
- 1 tablespoons mayonnaise
- ½ teaspoon apple cider vinegar
- ½ teaspoon Dijon mustard
- ½ tablespoon chopped chives
- ¼ teaspoon salt
- ⅛ ground black pepper
Instructions
- If you need to make fresh horseradish sauce, combine the sauce ingredients in a small bowl, and set aside.
- To caramelize the onions, heat olive oil in a pan over medium heat. When the oil is hot, add the onions, cook the onions but keep stirring them (gently) all the time to caramelize them. This takes about 20 minutes.
- In a pan warm up the prime rib briefly so it does not change color, this step is optional.
- Take the baguette, remove the ends, and slice into 4 inch pieces. Slice in half lengthwise to open them up.
- Spread horseradish sauce over each piece of baguette (top and bottom), then add sliced prime rib, followed by caramelized onions, and arugula. Finish off with a sprinkling of ground black pepper and serve.
Notes:
- You don’t have to use prime rib. This sandwich will be just as delicious made with any type of leftover roast beef!
- Plan Ahead. While you’re picking up the prime rib from the store, grab a baguette and some fresh arugula so you’ll be ready to make these sandwiches the next day.
- Slice Cold. Prime rib is much easier to slice thinly when it’s cold, rather than when it’s warm from the oven.
- Variations: Add thinly sliced tomatoes seasoned with salt and pepper, or make a hoagie-style prime rib sandwich by layering the meat with garlic mayo, tomato, lettuce, and provolone cheese.
- Other Greens: Use baby spinach, chopped romaine, or any other greens you enjoy in place of the arugula if you’d like.
Nutrition Information
This website provides approximate nutrition information for convenience and as a courtesy only. Nutrition data is gathered primarily from the USDA Food Composition Database, whenever available, or otherwise other online calculators.
© Little Sunny Kitchen
Geoff Charles says
Awesome sandwich