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prime rib french dip sandwich with au jus dipping sauce over white table

Prime Rib French Dip Sandwich

  • Author: Mike
  • Total Time: 30 minutes
  • Yield: 4 sandwiches 1x


Make Leftover Prime Rib shine with this easy and delicious recipe for prime rib sandwiches!


  • 1 1/3 lbs leftover prime rib, thinly sliced
  • 1 Tbsp butter
  • 1 white onion
  • 1/4 cup beef stock
  • salt and pepper, to taste
  • 4 hoagie rolls
  • 8 slices havarti cheese
  • leftover au jus (or two cups beefs stock simmered with two Tbsp flour)
  • horseradish sauce


  1. AU JUS: If you have leftover Au Jus, simple reheat it over medium high heat, reducing to low to keep warm.  If you do not, simply make some by mixing together 2 Tbsp flour and 1/4 cup of beef drippings.  Whisk together and continue up to 2 cups of beef stock 1/4 cup of at a time.  Season with salt and black pepper and reduce slightly.  Keep warm.
  2. SAUTE ONIONS:  Melt butter in a large saute pan (affiliate).   Add sliced onions and stir into the butter.  After the onions begin to slighten, season with salt and pepper.  Continue cooking until unions turn a soft golden brown, about 5 minutes.  Add 1/4 cup of beef stock and allow to absorb into onions.  Saute 3 more minutes and reduce heat to low to keep warm.
  3. TOAST BREAD:  Preheat oven broiler on high.  Place hoagie buns open side up on a large baking sheet (affiliate).  Place rolls in middle of oven and broil until inside of buns toasts to a golden brown.  Watch closely as they can burn quickly if left unattended.  Remove from oven and turn off broiler.
  4. MAKE SANDWICH:  Preheat oven to 400°.  Split about 1/4 of thinly sliced beef between the top and bottom.  On the top side, add a spoonful of sauteed onions.  Place a slice of cheese on to of each.  Place in preheated oven, open faced and toast about 5 minutes, or until cheese begins to brown.
  5. FINISHING TOUCHES:  Remove sandwiches from oven.  Spread horseradish sauce on one side of sandwich and squeeze together.  Serve immediately with warm au jus alongside in a small dipping cup.


  • While this recipe is best with leftover prime rib, obviously that’s not something you have in your fridge on the regular. So, you can easily use some alternatives. Obviously, other types of leftover roast beef will do, simply cut them think while cold and use the recipe just the same.
  • What if you don’t have any leftover beef but just want a sandwich? No problem, just get some roast beef. I suggest getting some London Broil from the meat counter from a quality brand like Boar’s Head.
  • Prep Time: 5 minutes
  • Cook Time: 25 minutes
  • Category: Main Course
  • Method: Baked
  • Cuisine: American

Keywords: leftover prime rib recipe, easy dinner recipe, french dip sandwich

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