Prime Rib French Dip Sandwiches | Great Leftover Recipe

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So, you have leftover prime rib and need a recipe? Look no further. Make an amazing Prime Rib French Dip Sandwich with this easy to follow recipe (with video!).

Prime Rib French Dip Sandwiches | Great Leftover Recipe | Nerd Chefs (1)

What is a French Dip Sandwich?

Actually an American invention, the French Dip Sandwich originated in Los Angeles. Two restaurants lay claim to making the original French Dip, Cole's Pacific Electric Buffet and Phillepe. So why is it called a French Dip if it's actually American? Because it's traditionally served on a baguette, a crusty french bread.

The sandwich is self is pretty straight forward. Shaved beef if piled high on and topped with onions and swiss cheese and served hot. Spread on some horseradish sauce along and a cup of au jus, a thin gravy made from the beef drippings for a flavor packed bite of goodness.

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Why you'll love this recipe

For this recipe, we'll use leftover Prime Rib from our recent Christmas dinner. I always buy mine a little bigger than is needed so I can make this awesome recipe the day or two after. This isn't just a great recipe for leftovers, it's the absolute perfect way to repurpose the crowned jewel of roast beef.

Now, I vary slightly from the traditional recipe in my version. Namely, bread choice. Instead of a super crusty bread, I opt for a soft hoagie roll, toasting the inside before baking hte sandwiches quickly. The result is a crispy bread that won't be soggy, but not so crunchy that it's crumbly. It's my favorite way to eat a french dip.

I'll also walk you through making an au jus, which is pretty simple to put together. You can make it from beef stock, or better yet, the pan drippings from your roasted prime rib.

Check out some of our other great recipes, like cajun shrimp and grits, smoked gouda mac and cheese, chicken tikka masala, or 29-hour, super tender sous vide chuck roast. Or, try one of my wife's favorites, my Bacon Lamb Sliders which are 100% flavor-bombs. .

Mike's Recipe Rundown

Taste: Rich, beefy flavor here is the primary flavor that comes through in every bite. By dipping the sandwich into a beefy and herby au jus gravy helps it really come through.
Texture: This recipe is a tad bit softer than your normal french dip. This is because we're using hoagie rolls instead of crusty french bread. But, it's far from soggy. We toast the inside to help the rolls keep their structural integrity. Meanwhile, the prime rib is super tender and the melted cheesy pulls nicely for a mouthwatering bite.
Difficulty - Pretty Easy! Since this recipe calls for using leftover prime rib, so most of the hard work (cooking the meat) is already done. This is mostly just broiling bread, stacking a sandwich and cooking it to perfection.
Pros: This is one of my absolute favorite leftover recipes. As good as prime rib is on the first shot, french dips are the best way to serve the same thing in a different way. Tons of flavor from a great cut of meat.
Cons: These don't make great leftovers, so only cook as many as you're planning on eating. You can always make more later.
Would I make it again? Yes! Since Prime Rib is basically a Christmas-only meal in our house, I always make this in the following days. But, as we'll get into, we can also make it year round with some other alternatives as well.

French Dip Sandwiches Tips and Tricks

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.
If you're more of a traditionalist, feel free to use a baguette instead of the hoagie buns we opt for. I would just skip the step of broiling the inside of the buns. The crustiness of the bread makes that unnecessary.

What you'll need to make Prime Rib French Dip Sandwiches

Equipment wise this one is pretty straight ahead. You'll want a good saute pan (affiliate) for cooking your onions down. Otherwise, a large baking sheet (affiliate) for heating the sandwiches in the oven is it. All stuff you should have laying around your kitchen.

As for ingredients, you'll want:

How to make a Prime Rib French Dip Sandwich

Prime Rib French Dip Sandwiches | Great Leftover Recipe | Nerd Chefs (2)

Au Jus

If you have leftover au jus, simply heat it in a small pot (affiliate) over medium-high heat. Reduce the heat to low to keep warm.

If you don't, you'll want to begin my mixing together 2 tbsp flour with ¼ cup of beef stock or pan drippings from your roasted meat. Whisk together over medium high heat in a small saucepan (affiliate).

Continue adding the stock ¼ at a time, stirring it in and allowing it to thicken slightly before adding more. Continue until all stock is added.

Season with salt and black pepper to taste and continue cooking over medium heat until reduced slightly. Keep warm until serving.

Sauteed Onions

Melt butter over medium heat in a saute pan (affiliate). Add sliced onions and stir into the butter. After a couple minutes the onions will soften slightly. Season with salt and pepper and continue stirring. Continue cooking over medium heat until onions turn a nice, golden brown, 5 minutes. Add ¼ cup of beef stock and allow onions to soak up. Saute an additional 3 minutes and remove from heat.

TIP: The longer you cook your onions over a medium to medium-low heat, the richer the flavor. They're good after 10 minutes, but sometimes I'll push it to 25 minutes to really develop some extra flavor.

Making the Sandwich

Place the hoagie buns with the inner side facing up on a large baking sheet (affiliate). Preheat oven broiler to high. When warm, place buns in middle rack and toast, watching carefully, until golden brown. They will go from barely toasted to burnt in a hurry, so watch closely.

Remove buns and turn off broiler. Next, preheat oven to 400°.

To assemble sandwich, split about ⅓ of a pound of leftover prime rib between the top and bottom bun. Top one side with a spoonful of sauteed onions. Top each side with a slice of havarti cheese. Toast open face until cheese melts, about 5 minutes.

Remove pan from oven. spread (or squeeze) horseradish sauce over top of sandwich and press top and bottom together. Serve immediately with warmed au jus in a small side cup for dipping.