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A prime rib sandwich on a piece of brown parchment paper.
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Leftover Prime Rib Sandwich

These delicious prime rib sandwiches are an easy way to use leftover prime rib roast!
Prep Time 10 minutes
Cook Time 25 minutes
Total Time 35 minutes
Servings 2 sandwiches

Ingredients

  • ¾ pound leftover cooked prime rib shaved or thinly sliced, fat trimmed and discarded
  • 2 tablespoons butter unsalted
  • 2 cups thinly sliced yellow onion sliced approximately ¼ inch thick
  • 2 hoagie or sandwich rolls approximately 7 inch rolls
  • cup prepared horseradish sauce more or less, to taste
  • 1 cup arugula tightly packed

Instructions

  • Melt butter in a large skillet or sauté pan over medium heat. Add onions and cook until onions are soft and caramelized, stirring occasionally, about 20 to 25 minutes. Decrease heat as necessary to prevent onions from burning. Remove from burner and set aside.
  • If sandwich rolls are not already sliced, slice them in half lengthwise.
  • Assemble sandwiches: Spread horseradish sauce on the tops and bottoms of sandwich rolls. On the bottom rolls, top each roll evenly with half of the arugula, sliced prime rib, and caramelized onions.

Notes

Helpful tip:  Slice the prime rib while it is cold or place it in the freezer for 20 to 30 minutes before slicing. This firms up the meat and makes it easier to slice.