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A Leftover Prime Rib Sandwich is the best way to enjoy your prime rib roast leftovers.

This recipe details how to make the best prime rib sandwich! Caramelized onions, dressed arugula greens, shaved leftover prime rib roast, and a roasted garlic horseradish mayo all come together for this incredible sandwich.

leftover prime rib sandwich recipe with grilled onions


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I look forward to enjoying a Leftover Prime Rib Sandwich almost as much as I enjoy eating the actual prime rib roast. Every Christmas our family makes a bone-in prime rib roast. If you’re not familar with prime rib, it’s an expensive cut of meat so you want to make sure you cook it perfectly. I absolutely love prime rib leftovers, so I always buy a roast bigger than what we’ll eat.

How to make a leftover prime rib sandwich:

This particular sandwich recipe is served cold. You can certainly warm the meat, but since I take great care to cook it perfectly the first time, I never want to risk over cooking the meat by reheating. I think leftover prime rib tastes best when thinly sliced.

There are a few ingredients that really make this sandwich recipe stand out.

  • I love mayo on my sandwiches and I love horseradish with my prime rib, so I combined the two! I also keep roasted garlic in my fridge at all times, so I added that as well.
bread topped with horseradish and mayo and roasted garlic for sandwich recipe
  • The caramelized onions are SO GOOD on this prime rib sandwich. The trick perfectly caramelizing your onions is to cook them as hot as you can without letting them burn and stirring them the least amount as possible. They take a little babysitting while on the stove, but they are so worth it.
dressed arugula greens on toast for sandwich recipe
  • Arugula is great on any sandwich, in my opinion, because this dark leafy green ads a nice bittery crunch. I always love to dress my salad greens with a bit of oil and vinegar.
grilled onions over shaved prime rib for sandwich

What else can you make with leftover prime rib?

We usually only have enough leftovers to make these sandwiches, but here are a few other recipe ideas to make with leftover prime rib:

  • Soup. Any soup that calls for beef can use leftover prime rib. My Instant Pot Beef Stew recipe would be outstanding with leftover prime rib. I would skip the step where you brown the stew meat and just throw everything in the . YUM!
  • Stroganoff. My Classic Beef Stroganoff or my Pressure Cooker Beef Stroganoff recipes could both be adapted to use leftover prime rib instead of ground or stew meat. Just skip the browning steps!
  • Hash. What’s better with eggs in the morning than a delicious hash? You could start with my Sweet Potato and Ham Hash and swap out the ham for prime rib and even use golden potatoes in place of the sweet potatoes.
recipe for the best leftover prime rib sandwich r

Leftover Prime Rib Sandwich

Prep5 minutes
Cook15 minutes
Total20 minutes
Servings 4 sandwiches
A Leftover Prime Rib Sandwich is the best way to enjoy your prime rib roast leftovers. This recipe details how to make the best prime rib sandwich!



  • To caramelize onions, melt butter in skillet over medium high heat. Add sliced onions, arrange in single layer, and don’t stir until they start to brown. Gradually reduce heat to prevent burning and only stir when they start to brown too much. Continue cooking until a dark caramel color forms. Set aside.
  • To make spread, combine mayonnaise and horseradish. I chose to set my roasted garlic cloves directly on the sandwich but you can mash and mix with the horseradish mayo, if you prefer.
    bread topped with horseradish and mayo and roasted garlic for sandwich recipe
  • In small bowl, dress arugla greens with olive oil and vinegar. Season with salt and pepper, if desired.
    dressed arugula greens on toast for sandwich recipe
  • To serve, layer sandwich with spread, dressed arugula, prime rib and caramelized onions. Serve cold.
    grilled onions over shaved prime rib for sandwich


Makes 4 sandwiches


Calories: 783kcal, Carbohydrates: 83g, Protein: 28g, Fat: 37g, Saturated Fat: 14g, Cholesterol: 69mg, Sodium: 802mg, Potassium: 546mg, Fiber: 4g, Sugar: 7g, Vitamin A: 415IU, Vitamin C: 11.4mg, Calcium: 118mg, Iron: 6.4mg

Nutrition information is automatically calculated, so should only be used as an approximation.

Did you make this? Leave me a comment below

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  1. 5 stars
    Thank you for such easy and tasty recipe, I followed it but made a few changes i heated up the meat on a baking dish tightly covered with foil for 10 minutes at 250F, I didn’t have horseradish so i used hot sauce and my family loved this sandwiches.

    1. Huh wow someone that actually might know how to make a sandwich, I’ll give it a try sounds great.
      Thank you

  2. 5 stars
    Can’t wait to try this recipe with my leftover Easter prime rib that was cooked to perfection. Reheating it would’ve been such a waste.

  3. 5 stars
    Meat and caramelized onions are made for each other. Add some bread and it gets better exponentially! Absolutely gorgeous sandwich, especially that last image!

  4. 5 stars
    Who would ever have leftover prime rib?? Kidding! I think I need to save some next time just for this. Delish!