This post may contain affiliate links. Please read our disclosure policy.
The best leftover prime rib sandwich is a great recipe for leftover prime rib roast. Served on a warm ciabatta roll topped with sweet caramelized onions, horseradish mayo, and seasoned fresh arugula- this will be your favorite prime rib leftovers!
Make our homemade ciabatta bread.
Prime Rib Sandwich
If you made prime rib roast for Christmas dinner or another time during the holiday season, this best leftover prime rib sandwich is the perfect way to use holiday leftovers. You can serve it with the optional au jus sauce if you want the extra touch.
Your tastebuds will go wild with this delicious sandwich’s delicious and fresh flavors.
Table of Contents
Simple Ingredients
It is a great option for leftovers from your prime rib dinner. A few basic ingredients make among the best prime rib sandwiches.
For the Sandwich:
- leftover prime rib (thinly sliced)
- Baguette bread
- Swiss cheese or provolone cheese (optional)
- Butter or olive oil for grilling or toasting
Caramelized Onions:
- Yellow onions, thinly sliced
- Butter
- Salt and Pepper to taste
- Pinch of Sugar (optional)
Horseradish Mayo:
- Horseradish sauce (adjust to taste)
- Mayonnaise
Salad:
- Baby arugula
- Olive oil
- Lemon juice
Optional Au Jus for Dipping:
- Reserved juices from the cooked prime rib
- Beef broth or beef stock (if needed)
- Salt and pepper to taste
See the recipe card for quantities.
How to Make Caramelized Onions (step-by-step photos)
See the recipe card below for the printable recipe.
Ingredients for caramelized onions.
Caramelize the Onions: In a pan, melt butter over medium-high heat. Add the thinly sliced onions and let them get brown on the bottom before turning.
Reduce heat to medium-low and simmer until they become soft and caramelized. This process can take 20-30 minutes.
Season with a pinch of sugar (optional), salt, and pepper to enhance the caramelization process. Stir occasionally.
How to Make Leftover Prime Rib Sandwich
Prepare the Horseradish Sauce: In a small bowl, mix horseradish sauce and mayonnaise. Adjust the ratio to your preferred level of spiciness. Set aside.
Toss the Salad: In a small bowl, toss the arugula with the olive oil and lemon juice until well coated. Set aside.
Assemble the Sandwich: Preheat a grill pan or skillet over medium heat. Alternatively, you can use a toaster or oven to toast the bread. Butter one side of each slice of bread.
Spread the horseradish-mayo sauce on the unbuttered side of one slice of bread.
Layer the thinly sliced prime rib and provolone or Swiss cheese on top (if using).
On the other slice of bread, spread the caramelized onions and cheese (if using).
Put the two slices of bread together with the spreads and fillings inside.
Cut the sandwich in half, and serve it with your favorite sides like coleslaw, pickles, or potato chips.
Substitutions
Steak Sandwich: use leftover pan-seared steak and create the same easy sandwich. You can also use leftover roast beef for more of a Philly cheese steak vibe, or think french dip sandwich.
Bread Substitutions:
- Use whole wheat, multigrain, or gluten-free bread if you have dietary preferences or restrictions.
- Substitute a sturdy lettuce leaf (like Romaine) or large cabbage leaves for a low-carb option.
Sauce Alternatives:
- Replace horseradish sauce with Dijon mustard, sour cream, barbecue sauce, or your favorite sandwich spread.
- Consider using aioli, pesto, or tzatziki for a unique flavor.
Variations
- Horseradish Cream and Pickled Onions: Instead of caramelized onions, use pickled red onions for a tangy and vibrant flavor. Spread a horseradish cream sauce on the bread for a bit of heat.
- Classic Philly Cheese Style: Slice the prime rib thinly and cook it with bell peppers and onions in a skillet. Add melted provolone cheese and serve on a crusty roll for a Philly cheesesteak-inspired sandwich.
- French Dip Style: Use a baguette and serve the prime rib sandwich au jus style. Dip the assembled sandwich into a bowl of hot beef broth before taking each bite.
- Blue Cheese and Arugula: Add crumbled blue cheese for a tangy and creamy twist. The peppery arugula complements the flavors beautifully.
- BBQ Prime Rib Sandwich: Dress the prime rib with your favorite barbecue sauce, coleslaw, and crispy fried onions for a tangy and crunchy sandwich.
- Horseradish and Smoked Gouda: Substitute the sliced provolone cheese or Swiss with smoked Gouda for a richer, smoky flavor. Double up on the horseradish sauce for extra zing.
- Italian Sub Style: Use ciabatta or baguette and layer the prime rib with sliced tomatoes, fresh basil, mozzarella cheese, and a drizzle of balsamic reduction.
- Mushroom and Swiss Redux: If you like mushrooms, sauté them with garlic and thyme, and add them to your sandwich along with Swiss cheese for a classic combination.
Storage
- Slice It: If you haven’t already, slice the meat to your desired thickness. This will help with even reheating and portion control.
- Wrap It Well: Wrap the sliced prime rib tightly in plastic wrap or aluminum foil to prevent air exposure and freezer burn.
- Airtight Container: Alternatively, place the wrapped prime rib slices in an airtight container. This provides extra protection against moisture and air.
- Refrigerate: Store the wrapped or containerized prime rib in the refrigerator for up to 3-4 days. If you plan to keep it longer, consider freezing it.
Top tips
- Choose the Right Bread: Select a sturdy bread like a baguette or ciabatta that can hold up to the juicy meat and toppings.
- Balance Flavors: Consider the balance of flavors and textures in your sandwich. Sweet, tangy, creamy, and crunchy elements can all enhance the experience.
- Layering Matters: Arrange the ingredients thoughtfully. Place condiments and spreads on the bread’s interior to prevent sogginess, and evenly distribute the prime rib, cheese, and vegetables for each bite.
- Sauce Placement: If using au jus or another sauce, consider dipping it on the side to prevent the bread from getting too soggy.
- Toast the Bread: Toasting the bread adds a delightful crunch and helps keep it from becoming overly soft from the sandwich fillings.
FAQ
To prevent a soggy sandwich, apply condiments and spreads to the interior of the bread slices rather than directly on the prime rib. Using a layer of greens (e.g., arugula or lettuce) can act as a barrier to keep the bread from getting too moist. Additionally, consider toasting the bread to create a more resilient surface.
A crusty baguette or ciabatta is often preferred for a prime rib sandwich due to its sturdiness and texture. A toasted hoagie roll or hoagie bun also work.
More Recipes
Looking for other recipes like this? Try these:
What to Serve with Leftover Prime Rib Sandwich
Side dishes to serve with leftover prime rib sandwich recipe:
More on this post: What to Serve with Prime Rib.
Print
Best Leftover Prime Rib Sandwich Recipe
The best leftover prime rib sandwich is a great recipe for leftover prime rib roast. Served on a warm ciabatta roll topped with sweet caramelized onions, horseradish mayo, and seasoned fresh arugula- this will be your favorite prime rib leftovers! Make our homemade ciabatta bread.
- Total Time: 40 minutes
- Yield: 4 servings 1x
Ingredients
Sandwich:
- 12–15 oz of leftover prime rib (thinly sliced)
- 4 ciabatta rolls or 8 slices of baguette bread
- 4 slices swiss cheese or provolone cheese (optional)
- Butter or olive oil for grilling or toasting
Caramelized Onions:
- 2 large yellow onions, thinly sliced
- 2 tablespoons butter
- Salt and Pepper to taste
- Pinch of Sugar (optional)
Horseradish Mayo:
- 1–2 tablespoons horseradish sauce (adjust to taste)
- 2–3 tablespoons mayonnaise
Salad:
- 2 cups arugula or baby arugula
- 1 tablespoon olive oil
- 1 teaspoon lemon juice
Optional Au Jus for Dipping:
- Reserved juices from the cooked prime rib
- Beef broth or beef stock (if needed)
- Salt and pepper to taste
Instructions
- Caramelize the Onions: In a pan, melt butter over medium-high heat. Add the thinly sliced onions and let them get brown on the bottom before turning. Reduce heat to medium-low and simmer until they become soft and caramelized. This process can take 20-30 minutes. Season with a pinch of sugar (optional), salt, and pepper to enhance the caramelization process. Stir occasionally.
- Prepare the Horseradish Sauce: In a small bowl, mix horseradish sauce and mayonnaise. Adjust the ratio to your preferred level of spiciness. Set aside.
- Toss the Salad: In a small bowl, toss the arugula with the olive oil and lemon juice until well coated. Set aside.
Assemble the Sandwich:
- Preheat a grill pan or skillet over medium heat. Alternatively, you can use a toaster or oven to toast the bread. Butter one side of each slice of bread.
- Spread the horseradish-mayo sauce on the unbuttered side of one slice of bread.
- Layer the thinly sliced prime rib and provolone or Swiss cheese on top (if using).
- On the other slice of bread, spread the caramelized onions.
- Put the two slices of bread together with the spreads and fillings inside.
- Cut the sandwich in half, and serve it with your favorite sides like coleslaw, pickles, or potato chips.
Serve with Optional Au Jus:
- In a small saucepan, heat the reserved juices from the cooked prime rib. If needed, add a bit of beef broth to adjust the consistency. Season the au jus with salt and pepper to taste.
- Serve the sandwich with a side of the optional au jus for dipping.
- Prep Time: 5 min
- Cook Time: 30-35 minutes
- Category: Savory
- Method: American
- Cuisine: American
This is a phenomenal sandwich, all the component come together so great, I would make prime rib just so I can make it again!
Yes! Thanks so much!
I’m anxious to try this recipe. Can I use the same technique but form it into rolls instead of loaves?
Yes! Absolutely
So good with leftover prime rib! The caramelized onions add the best flavor.