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Leftover prime rib sandwich recipe.
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5 from 1 vote

Leftover Prime Rib Sandwich

Take one bite of this leftover prime rib sandwich and you will be looking for excuses to make more prime rib roasts.
Prep Time5 mins
Cook Time30 mins
Total Time35 mins
Course: Sandwich
Cuisine: American
Servings: 2
Calories: 1057kcal



  • 1 pound leftover prime rib thinnly sliced
  • 1 sweet onion sliced
  • 1 tablespoon butter
  • cup arugula
  • 2 hoagie rolls

Creamy Horseradish Sauce

  • 2 tablespoons mayo
  • 1 tablespoon prepared horseradish
  • 1 teaspoon Dijon mustard
  • 1 garlic clove minced
  • ¼ teaspoon fresh ground pepper


  • Add sliced onions to a saute pan along with butter and set over medium heat.
  • Saute onions until they turn brown and sticky, stirring on occasion to prevent burning. Approximately 30 minutes.*
  • While onions caramelize, prepare your horseradish sauce by mixing the sauce ingredients together in a small bowl, then set aside.
  • Lightly toast the interior of the hoagie roll by setting it face down in a hot skillet for 1-2 minutes.
  • Assemble the sandwich by spreading the arugula along the bottom of the cut side of the bread, then top with sliced prime rib, caramelized onions, and horseradish sauce. Serve immediately.


*You can't rush caramelizing onions. The longer you take to caramelize them the sweeter the flavor will be.
If you wish to enjoy this as a warm sandwich I recommend gently heating leftover au jus (or use beef stock) in a saucepan until it reaches around 120 degrees, then soak the meat slices in the liquid to warm them. You don't want to heat the au jus too hot or it will cook the slices.


Calories: 1057kcal | Carbohydrates: 47g | Protein: 38g | Fat: 79g | Saturated Fat: 30g | Polyunsaturated Fat: 9g | Monounsaturated Fat: 30g | Trans Fat: 0.3g | Cholesterol: 158mg | Sodium: 601mg | Potassium: 746mg | Fiber: 3g | Sugar: 13g | Vitamin A: 268IU | Vitamin C: 11mg | Calcium: 74mg | Iron: 15mg