Vegetarian French Dip Sandwiches

Last week I saw an amazing photo for some Slow Cooker French Dip Sandwiches from Carlsbadcravings.com and I couldn’t stop thinking about them. I wanted those sandwiches and I wanted them bad. But then I thought, “What if I tried to make vegetarian French dip sandwiches?” and then I was on a mission. The recipe turned out really amazing on the first try. So amazing, in fact, that this is the most enthusiastic that I’ve seen my boyfriend about any recipe that I’ve made for him so far. And I’ve fed him a lot of them. ;)

Vegetarian French Dip Sandwiches

Two Vegetarian French Dip Sandwiches on brown paper, next to a small dish of broth for dipping

How to Make a French Dip Sandwich Vegetarian

I replaced the tender beef in classic French Dip sandwiches with meaty strips of portobello mushrooms. But, because portobellos can be quite pricey, I added in a sliced onion for a little inexpensive bulk.

I’d normally add a little Worcestershire to the broth of a beef French dip, but that has anchovies in it. So, to mimic the salty-sweetness of Worcestershire I added a little soy sauce and just a smidge of brown sugar. That hint of sweetness from the brown sugar really helped balance the flavors and made the broth complex, so don’t be tempted to skip it.

Also, I highly suggest using Better Than Bouillon for your broth. It has a deep flavor and just the right amount of salt.

How to Store Vegetarian French Dip Sandwiches

If you’re not eating these sandwiches all at once, store the mushroom and onions in the broth and reheat them together before piling the filling into the sandwiches and dipping into the remaining broth. You can heat these sandwiches in a matter of minutes under the broiler, so it’s a nice quick meal for leftovers!

What Kind of Bread Should I Use?

Oh, one last note. Due to pricing and product availability I did not use a French loaf for my sandwiches (I know, I know). Instead I bought a pack of long ciabatta rolls that worked quite well. The key to choosing your bread for these sandwiches is to make sure you have something very sturdy and crusty so that it holds up to dipping in the delicious au jus.

 
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4.95 from 40 votes

Vegetarian French Dip Sandwiches

These Vegetarian French Dip Sandwiches are fast, easy, and feature a salty-sweet herb infused vegetarian au jus for dipping. 
Keyword: Hot Sandwich
Total Cost: $10.44 recipe / $2.61 serving
Author: Beth M
Prep Time: 10 mins
Cook Time: 25 mins
Total Time: 35 mins
Servings: 4

Ingredients

  • 1 yellow onion ($0.25)
  • 3 portobello mushroom caps (about 1 lb.) ($5.39)
  • 2 Tbsp butter ($0.22)
  • Pinch of salt and pepper ($0.05)
  • 1/4 tsp dried thyme ($0.03)
  • 1/4 tsp dried oregano ($0.03)
  • 2 cups vegetable broth* ($0.28)
  • 1 Tbsp soy sauce ($0.09)
  • 1/2 Tbsp brown sugar ($0.02)
  • 1/8 tsp garlic powder ($0.02)
  • 4 6-inch French or Ciabatta rolls ($2.66)
  • 4 slices provolone ($1.40)

Instructions

  • Slice the onion into thin strips. Rinse the portobello caps to remove any dirt or debris. Slice each cap in half, then crosswise into 1/4-inch thick strips.
  • Add the butter to a deep skillet along with the sliced onions. Sauté the onions over medium heat for a few minutes, or just until they begin to soften. Add the sliced mushrooms, a pinch of salt and pepper, the thyme, and oregano. Sauté the mushrooms until they release all their moisture and the liquid in the bottom of the skillet has dried up (about 10 minutes). You want to see some of the liquid browning and coating the bottom of the skillet (but not burning).
  • Once the evaporated juices begin to coat the bottom of the skillet, pour in the vegetable broth. Stir to dissolve the browned bits from the bottom of the skillet. Also add the soy sauce, brown sugar, and garlic powder. Allow the liquid to come up to a simmer, then turn down to low and simmer for about 5 minutes while you toast the bread.
  • Open the rolls and place them on a baking sheet, open sides up. Turn the oven on to broil and place the rolls in the oven. Watch the rolls closely and broil just until you see a slightly browning on the edges (about 5 minutes).
  • Use a slotted spoon or tongs to take the mushrooms and onions out of the au jus. Divide the mushrooms and onions among the four rolls. Top each sandwich with a slice of provolone. Return the sandwiches to the oven and broil for a few minutes more, or just until the cheese is melted. Close the sandwiches up and serve with the au jus from the skillet for dipping.

Notes

*The type of broth you use will greatly affect the end flavor of the au jus. I used vegetable flavored Better Than Bouillon concentrate to make my broth.
Tried this recipe?Mention @budgetbytes or tag #budgetbytes on Instagram!

I’m definitely going to be making this recipe OFTEN. 

Close up of a Vegetarian French Dip Sandwich being dipped into a bowl of broth

Side view of a Vegetarian French Dip Sandwich with a bowl of broth and second sandwich in the background

Make sure to check out our Vegetarian Recipe Archives and Vegan Recipe Archives for more vegetarian deliciousness!!

Step by Step Photos

Sliced Mushrooms and Onions on a cutting board

Slice one yellow onion into thin strips. Wash and slice three portobello caps. I used three caps, which weighed 0.9 lbs. total. I like to slice them in half, then crosswise into strips so that the strips aren’t super long.

Sauté Onions in the skillet

Add the onions and 2 Tbsp butter to a deep skillet. Sauté the onions over medium heat just until they begin to soften (about 3 minutes).

Add Mushrooms and Herbs to the skillet

Then add the sliced mushrooms, a pinch of salt and pepper, 1/4 tsp dried oregano, and 1/4 tsp dried thyme.

Sauté Mushrooms until browned and coating skillet

Sauté the mushrooms and onions until the mushrooms release all their moisture and the liquid in the bottom of the skillet evaporates. You’ll notice as you begin to sauté the mushrooms that it will seem dry at first, then they’ll suddenly start releasing moisture and it will pool in the bottom of the skillet. Keep sautéing until that liquid dries up and begins to coat the bottom of the skillet. That brown stuff stuck to the bottom of the skillet is caramelized and is where you’ll get a lot of flavor for the au jus.

Add Broth Soy Sauce Brown Sugar Garlic Powder to the skillet with the mushrooms

Once you start to get that browning on the bottom of the skillet, pour in 2 cups vegetable broth and stir to dissolve the browned bits off the bottom. Then add 1 Tbsp soy sauce, 1/2 Tbsp brown sugar, and 1/8 tsp garlic powder.

Simmar Au Jus

Let the au jus come up to a simmer, then turn it down to low and let it simmer for 5-10 minutes while you toast the bread.

Toast Bread in the oven on a baking sheet

Place four opened French or ciabatta rolls on a baking sheet, open side up. Turn the oven on to broil and toast the bread under the broiler just until you start to see a little browning on the edges. I kept my oven rack in the middle so that the bread was far enough away from the broiler that it wouldn’t toast super fast. That gives you a little more room for error. ;)

Lift Mushrooms from au jus with tongs

Use tongs or a slotted spoon to pick the mushrooms and onions up out of the au jus.

Add Mushrooms and Onions to rolls

Pile the mushrooms and onions onto the rolls…

Add Provolone Cheese to sandwiches before broiling

Add a slice of provolone to each…

Melt Cheese Under Broiler

Then return the sandwiches to the broiler to melt the cheese. The open bread will continue to brown here, so if your bread was a little more on the brown side after the first broil, flip the pieces over so they’ll brown on top instead.

Finished Vegetarian French Dip Sandwiches viewed from the side, melted cheese and a mushroom strip hanging out

Finally, close up the sandwiches and serve while hot! But don’t forget to ladle that yummy au jus into little bowls for dipping.

Two Vegetarian French Dip Sandwiches on brown paper with a bowl of broth on the side

These Vegetarian French Dip Sandwiches are seriously good stuff. nomnomnom