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
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.
Vegetarian French Dip Sandwiches
- 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)
- 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.
Nutritional values are estimates only. See our full nutrition disclosure here.
I’m definitely going to be making this recipe OFTEN.
Step by Step Photos
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.
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).
Then add the sliced mushrooms, a pinch of salt and pepper, 1/4 tsp dried oregano, and 1/4 tsp dried thyme.
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.
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.
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.
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. ;)
Use tongs or a slotted spoon to pick the mushrooms and onions up out of the au jus.
Pile the mushrooms and onions onto the rolls…
Add a slice of provolone to each…
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.
Finally, close up the sandwiches and serve while hot! But don’t forget to ladle that yummy au jus into little bowls for dipping.
These Vegetarian French Dip Sandwiches are seriously good stuff. nomnomnom