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Leftover Prime Rib Sandwich Recipe

Leftover Prime Rib Sandwich

Transforming Prime Rib Leftovers into a Culinary Masterpiece: The Ultimate Leftover Prime Rib Sandwich Recipe. In under 20 minutes, you'll transform humble leftovers into a gourmet sandwich experience. Prepare for a tender, juicy prime rib nestled between perfectly toasted bread, elevated by a rich cheese and a zesty horseradish kick.
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Prep Time 15 minutes
Cook Time 5 minutes
Total Time 20 minutes
Servings: 4 sandwiches
Course: Sandwich
Ingredients Equipment Method Notes

Ingredients
  

Leftover Cooked Prime Rib
  • 1.5 pounds leftover cooked prime rib thinly sliced
Hoagie Rolls or Sturdy Artisanal Bread
  • 4 hoagie rolls or sturdy artisanal bread slices
Butter and Garlic
  • 2 tablespoons unsalted butter softened
  • 1 clove garlic minced (optional, for toasting bread)
Cheese
  • 1 cup shredded Gruyère cheese (or Swiss or Provolone)
Caramelized Onions
  • 1/2 cup caramelized onions (see tip below)
Sauces and Seasonings
  • 1/4 cup horseradish sauce (store-bought or homemade)
  • 2 tablespoons Dijon mustard
  • 1 tablespoon fresh parsley chopped (for garnish, optional)
  • Salt and freshly ground black pepper to taste
  • 1 tablespoon butter for warming prime rib (optional)
  • 1 splash beef broth or water for warming prime rib (optional)
  • 1 large yellow onion thinly sliced (for caramelizing, if not pre-made)
  • 1 tablespoon butter or olive oil for caramelizing onions

Equipment

  • Skillet
  • Griddle
  • Baking Sheet

Method
 

  1. Ensure your leftover prime rib is thinly sliced against the grain for maximum tenderness. If your prime rib is cold, you can gently warm it in a skillet over medium-low heat with a tablespoon of butter and a splash of beef broth or water until just heated through. Be careful not to overcook it, as it’s already cooked. Season lightly with salt and pepper if needed.
    1.5 pounds leftover cooked prime rib, 1 tablespoon butter, 1 splash beef broth or water, Salt
  2. If you don't have pre-caramelized onions, this is your chance to add an extra layer of gourmet flavor. Thinly slice one large yellow onion. Heat 1 tablespoon of butter or olive oil in a skillet over medium-low heat. Add the onions and cook slowly, stirring occasionally, for 20-30 minutes, or until they are deeply golden brown and sweet. Season with a pinch of salt.
    1 large yellow onion, 1 tablespoon butter or olive oil, Salt
  3. Slice your hoagie rolls lengthwise. If using, rub the cut sides with the minced garlic clove for an extra aromatic boost. Spread softened butter evenly on the cut sides of the rolls.
    4 hoagie rolls or sturdy artisanal bread slices, 1 clove garlic, 2 tablespoons unsalted butter
  4. Place the buttered bread slices, cut-side down, in a clean skillet or on a griddle over medium heat. Toast until golden brown and lightly crispy. Alternatively, you can toast them under the broiler for a minute or two, watching them very carefully to prevent burning.
  5. On the bottom half of each toasted roll, spread a generous layer of horseradish sauce.
    1/4 cup horseradish sauce
  6. Arrange the thinly sliced prime rib evenly over the horseradish sauce. Don't be shy; pack it in for a truly decadent sandwich.
    1.5 pounds leftover cooked prime rib
  7. Next, scatter the sweet caramelized onions over the prime rib.
    1/2 cup caramelized onions
  8. On the top half of each roll, spread the Dijon mustard.
    2 tablespoons Dijon mustard
  9. Place the cheese shreds over the prime rib and onions on the bottom halves of the rolls.
    1 cup shredded Gruyère cheese
  10. Close the sandwiches with the top halves of the rolls. Place the assembled sandwiches back into the skillet (if there's enough fat and flavor left from the bread toasting), or onto a baking sheet, over medium-low heat. Cover the skillet with a lid or tent the baking sheet loosely with foil to help the cheese melt evenly. Cook for 3-5 minutes, or until the cheese is wonderfully melted gooey, and the bread is heated through.
  11. Carefully remove the sandwiches from the skillet or oven. If desired, sprinkle with fresh chopped parsley for a touch of color and freshness. Slice in half and serve immediately.
    1 tablespoon fresh parsley

Notes

Store unassembled components separately in airtight containers in the refrigerator for up to 3-4 days. Horseradish sauce and Dijon mustard can be stored in the fridge for about a week. Reheat assembled sandwiches in a skillet over medium-low heat, covered, or in a preheated oven at 350°F (175°C) for 5-10 minutes. Freezing assembled sandwiches is not recommended.