Thin slices of roast beef, gooey cheese, and caramelized onions make this the best french dip sandwich ever! Serve with a side of au jus and get ready to fall in love. After one bite, it’s impossible to put this sandwich down.

The King of French Dip Recipes…

Say hello to the coziest, heartiest, most delicious french dip sandwich ever! I love making this recipe on snowy days, game days, or when we have friends over. It’s also great for hosting large family gatherings. Because these sandwiches are:

1. Super fun to make and eat
2. pretty easy to whip up
3. and incredibly delicious!

Between their ultra savory flavor and hearty portion-size, they’ll keep you full and satisfied for hours!

How to Make a French Onion Dip: Ingredients

• French Baguette: Or use french rolls or french bread. If you don’t know the difference, I dive into the differences between these bread options below.
• Roast Beef: Use thinly sliced deli roast beef or prepare a rump roast and cut it into thin slices.
• Butter: Adds a rich flavor to the au jus, I don’t recommend leaving it out.
• Fresh Thyme: Use the leaves only! And finely chop them.
• Yellow Onions: Reach for large onions that feel firm and fresh.
• Spices: Salt, pepper, and red pepper flakes add the right amount of seasoning.
• Cooking Sherry: In a pinch, white wine or red wine will make a fine substitute.
• Beef Stock: I love using beef stock or beef bone broth for extra rich flavor. Beef broth will work in a pinch.
• Cornstarch: Just a tiny amount thickens the au jus.
• Water: You’ll mix this with the cornstarch to form a slurry.
• Gruyere Cheese: This cheese provides the most delicious and sophisticated flavor. But thin slices of Swiss cheese or provolone cheese will also work.

How to Make French Dip Sandwiches: Method

1. Prepare the Bread: Slice and place on aluminum foil until needed.
2. Preheat the Oven: Give your oven about 20 to 30 minutes to reach 500 degrees (F). 
3. Add the Roast Beef: Divide the thin slices of roast beef evenly among the bread.
4. Make the Au Jus: Don’t skimp on time when caramelizing the onions. This is what gives the au jus so much flavor.
5. Scoop out the Onions: Use a slotted spoon to scoop the onions out of the broth. Or drain the sauce through a fine mesh strainer. Be sure there’s a clean bowl underneath to catch the au jus.
6. Divide the Au Jus: Divide the au jus into individual ramekins or small bowls.
7. Make the Sandwiches: Divide the onions and shredded cheese on top of the sandwiches. Wrap with foil and place them on a baking sheet.
8. And Bake: Place the pan in the oven or 5 minutes. Carefully unwrap the sandwiches and serve with a side of au jus!

Roast Beef Lunch Meat vs Rump Roast

• If you have access to a deli where they’ll slice you fresh roast beef, it’s the easiest choice.
• I don’t suggest using packaged roast beef, however it will technically work.
• You could also buy a rump roast and cook it yourself. Then trim off an excess fat, thinly slice it, and use it in these sandwiches.

French Rolls or Bread?

• French rolls or bread and baguette can all seem pretty similar on the surface. And at the end of the day, they’re all solid choices for French dip recipes. 
• I like to use baguette, a style of French bread. I choose baguette for this because it has a thicker, crispier crust. Which helps the sandwiches avoid getting soggy. 
• French bread will also work, but it has a softer crust and interior, which will make this a softer sandwich. And could allow for sogginess if the sandwich sits too long. 
• You could also use French rolls. Similar in taste and texture to French bread, but in smaller individual portions, instead of a giant loaf. 
• French rolls will work great for this recipe as long as you plan on eating it sooner than later. Because the longer it sits, the higher chance it’ll become soggy. 

Serve with a side of Au Jus

• Au jus is a French culinary term that translates to: “with juice.” 
• Typically, it’s a savory broth that’s made by using the drippings from meat.
• My au jus recipe doesn’t call for meat drippings, because I typically “cheat” and use sliced deli meat. 
• To give the au jus plenty of flavor, I use beef broth, fresh thyme, and cooking sherry. 
• Some readers have reported enjoying the addition of a teaspoon of soy sauce or Worcestershire sauce. Feel free to add a teaspoon for a deeper flavor. 

Can I make this a Slow Cooker French Dips?

I know people love to make slow cooker french dip sandwiches. So I wanted to offer an option on how I would go about that using this recipe.

1. I suggest doubling or tripling the recipe if you plan on making them into slow cooker french dips. This makes it perfect for larger crowds.
2. Make the french onion au jus sauce first. Place the sauce, including the onions, inside your slow cooker on the “warm” setting. Or whatever setting is equivalent.
3. 30 minutes before your guests arrive, add the roast beef into the au jus. Stir well and cover the slow cooker.
4. Before your guests arrive, place the baguette, french rolls or bread on a large cutting board.
5. You can also place out a variety of cheeses if you’d like to give your guests options. Such as Swiss cheese, provolone cheese, or gruyere cheese.
6. When you’re ready to serve the sandwiches, fire up your oven to 500 degrees.
7. Allow your guests to make their own sandwiches, or make them for them. Then wrap them on foil and bake for about 5 minutes.
8. Scoop out some of the au jus and place it into small bowls. Serve with a side of au jus and plenty of napkins.

I love adding a small salad on side. I usually make a simple dressing with olive oil, garlic, and lemon juice. But serve them with whatever you feel is best!