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Close-up of a delicious leftover prime rib sandwich featuring medium-rare slices, arugula, red onion, and creamy sauce on a baguette.

Leftover Prime Rib Sandwiches with Cracked Pepper Horseradish Cream Sauce

Make sandwiches using leftover prime rib roast, served on a baguette with arugula, red onion, and a homemade horseradish cream sauce.
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Prep Time 10 minutes
Cook Time 10 minutes
Assembly Time 5 minutes
Total Time 25 minutes
Servings: 4 sandwiches
Course: Dinner, Lunch
Cuisine: American
Calories: 564
Ingredients Equipment Method Notes

Ingredients
  

Prime Rib Sandwiches
  • 1 lb prime rib roast shaved or thinly sliced
  • 1 large baguette or 2 smaller deli loaves
  • 2 cups arugula or mixed baby greens
  • 1 medium red onion sliced
  • 8 slices provolone cheese optional
  • 1 drizzle au jus optional or use beef stock
Cracked Pepper Horseradish Cream Sauce
  • 1/2 cup sour cream or greek yogurt
  • 1 tablespoon horseradish
  • 1/2 tablespoon Dijon mustard
  • 1 teaspoon lemon juice
  • 1/2 teaspoon kosher salt or to taste
  • 1/2 teaspoon freshly ground black pepper or to taste

Equipment

  • Oven
  • Aluminum foil
  • Baking dish or cast iron skillet
  • Small bowl

Method
 

  1. Preheat your oven to 300°F (145°C) if you plan to serve the sandwiches warm. Wrap your leftover prime rib in an aluminum foil pouch. Add a drizzle of beef stock or leftover prime rib au jus, then seal the meat securely in the foil.
  2. Place the foil pouch into a baking dish, cast iron skillet, or a rimmed baking sheet. Set the meat on the center rack of your preheated oven and warm the prime rib for 10 minutes, or until it reaches your desired temperature.
  3. While the prime rib reheats, mix the cracked pepper horseradish cream sauce in a small bowl. Add all sauce ingredients and mix until they are evenly distributed. Taste the sauce and adjust seasoning or add more horseradish if you prefer more heat. Cover and refrigerate the sauce if you plan to use it later.
  4. Trim the ends from your baguette and cut it into 4 equal sandwich portions. Slice each piece horizontally, being careful not to cut all the way through the bread.
  5. Spread the cracked pepper horseradish cream sauce on both the top and bottom halves of the bread pieces. Stuff the bread with the sliced prime rib. Top with optional provolone cheese slices, arugula, and red onion slices. Close the sandwich and serve.

Notes

You can use a crusty baguette or a par-baked sourdough loaf for this sandwich. The flavor of sourdough works well with the prime rib and horseradish cream sauce.
Add roasted garlic to your horseradish sauce for extra flavor. Melt 4 tablespoons of butter in a large skillet over medium heat to make caramelized onions. Add 2 sliced sweet yellow onions and saute for 1 minute, then reduce the heat to low. Cook until the onions are browned, stirring occasionally. This usually takes up to 30 minutes.
If you are serving the sandwiches warm with cheese, leave the oven on. You can return the open-faced sandwiches, topped with prime rib and cheese, to the oven to quickly melt the provolone for 2 to 3 minutes.