Portobello French Dip with Horseradish Aioli Recipe - Skillful Cook
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Portobello French Dip with Horseradish Aioli

60 reviews / 5 average

Roasty portobello strips, golden caramelized onions, melted Provolone cheese, zippy horseradish aioli, all piled on a warm, crusty roll.

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It's hard to describe how much there is to love about these sandwiches, but I'll try:

Crunchy, buttery, toasted bread is going to meet up with roasted steak-seasoned portobello strips, sweet and golden caramelized onions, a sheet of melted Provolone, and a big thick smear of horseradish aioli...

And then just when you think it can't even get any better, that whole beautiful crispy, saucy, golden sandwich gets dunked in a richly savory, no-meat-necessary, au jus dipping sauce.

Ingredients for portobello french dip.

It is wonderful, it is meatless, it is the epitome of comfort food.

Dipping portobello french dip into au jus.

Watch How To Make This Recipe:

French dips are a type of sandwich that normally contain beef, onions, and cheese (also called beef dips) and their trademark is that they get dipped in an au jus (brothy kind of sauce). According to this nice little history of French dips, they are an American invention, but they're called French due to the type of bread usually used.

Common Questions About French Dips

What can I substitute for Worcestershire sauce?

You can use vegan Worcestershire sauce or substitute soy sauce.

What can I use instead of white wine?

You could add a little bit of water instead.

How can I make this gluten-free?

We'd suggest using gluten-free Worcestershire sauce, tamari or coconut aminos in place of soy sauce, and using a gluten-free baguette or roll.

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A picture of Portobello French Dip with Horseradish Aioli

Portobello French Dip with Horseradish Aioli

  • Author: Lindsay
  • Total Time: 45 minutes
  • Yield: 4 mega sandwiches 1x


These Portobello French Dips are about to change your life! Roasty portobello strips, golden caramelized onions, melted Provolone cheese, zippy horseradish aioli, all piled on a warm, crusty roll.



Roasted Mushrooms

  • 4 portobello mushroom caps, sliced into thin strips
  • 2-3 tablespoons olive oil
  • 1-2 teaspoons Montreal steak seasoning (or just a sprinkle of salt and pepper)

Caramelized Onions and Au Jus

  • 2 tablespoons butter
  • 1 large onion, thinly sliced
  • 1/4 cup white wine
  • 1 tablespoon Worcestershire (omit for vegetarian / vegan)
  • 1 tablespoon soy sauce 
  • 2 cups beef or vegetable broth
  • salt, pepper, and a pinch of sugar to taste

Horseradish Aioli

  • 1/2 cup mayo
  • 1 teaspoon horseradish
  • 1 clove garlic, grated
  • pinch of salt

French Dip Essentials

  • 4 crusty sourdough rolls, or a baguette cut into 4 sections 
  • Provolone cheese slices


  1. Roast the Mushrooms: Preheat oven to 450 degrees. Toss mushroom slices with oil and seasoning. Roast for 20-30 minutes. 
  2. Caramelize the Onions: Meanwhile, melt the butter in a large skillet over medium heat. Add onions; saute until softened, then turn the heat down to caramelize the onions for 20 minutes or so, stirring occasionally until they are deep golden brown.
  3. Make the Au Jus: Add the wine to the onions in the pan. Let it sizzle out. Add the Worcestershire and soy sauce. Add the broth. Simmer until reduced slightly. Pull out the onions with tongs and set aside. Season the au jus to taste.
  4. Toast the French Dips: Butter the bread if you want. Pile mushrooms on the bread. Cover with cheese. Return to the oven on the same roasting pan for about 5 minutes (enough to toast the bread and melt the cheese). 
  5. Feast: Top the sandwiches with caramelized onions. Give em each a dollop of horseradish aioli. Serve with the au jus for dipping! HOLY MOLY that's good.


  • Prep Time: 15 minutes
  • Cook Time: 30 minutes
  • Category: Sandwich
  • Method: Oven
  • Cuisine: American

Keywords: portobello mushrooms, french dip, vegetarian sandwich, caramelized onions

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Instagram images of portobello french dips.

One More Thing!

This recipe is part of our collection of delicious mushroom recipes. Check it out!

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  1. Skillful Cook Logo

    Oh my gosh, I have been talking for the last few weeks about being uninspired with my cooking. This is EXACTLY what I needed to get super excited about a meal and out of my rut! I cannot wait to make these – YUM!!

  2. Skillful Cook Logo

    OK, it’s barely past breakfast time, and I am drooling for one of these!!!

    Adding a stop at the local grocery to my list today, to snag those mushrooms and some bread… THANK YOU!

  3. Skillful Cook Logo

    What do you line your baking sheet with in the video. ( It isn’t just parchment paper.)

    1. Skillful Cook Logo

      Hi Dale! It doesn’t look like we’ve used any lining on the baking sheets. It could be the texture/pattern of the baking sheet that you’re seeing.

  4. Skillful Cook Logo

    I just made these and they are excellent. They were easy and so fulfilling to eat. Thank you…..

    1. Skillful Cook Logo

      It definitely adds a nice rich flavor, but you could just use more broth instead!

  5. Skillful Cook Logo

    Another amazing recipe. This is really soooooo good. I used apple cider vinegar since I didn’t have any white wine laying around. It was great!! Thank you for all of your recipes.

  6. Skillful Cook Logo

    This was so amazing! My 6 year old and 4 year old kept asking for bites so I had to make them their own, and my 4 year old finished and told me he would eat these everyday! Got them to eat veggies without begging them to finish!

  7. Skillful Cook Logo

    Made this as soon as I saw it! It was SO good. It was impossible to eat, in the best possible way. Easy and quick enough to make on a weeknight. My only frustration was after roasting the mushrooms, I had no where near enough for 2, let alone 4 sandwiches. I used four pretty decent sized portobello mushrooms. But they shrunk SO much. I ended roasting a bunch of white mushrooms to be able make up enough for two sandwiches. But otherwise it was a great meal!

    1. Skillful Cook Logo

      I thought these were soooo delicious but I had a similar issue where I actually roasted 6 portobello caps and only had enough for 2 sandwiches because they shrunk up so much in the oven. I was so disappointed because I was reaaally looking forward to a leftover sandwich!! 🙂 it was yummy!!

      1. Skillful Cook Logo

        Glad you enjoyed the recipe! And thanks so much for the feedback, Megan!

        1. Skillful Cook Logo

          This was SO good! I also agree with other commenters that the mushrooms not being enough for four sandwiches. Two sandwiches was very filling for two people but would have loved to have had leftovers.

  8. Skillful Cook Logo

    Made these last night, so satisfying, even my carnivorous husband loved them! Next time I will slice the portobellos a bit thicker so they don’t shrink down as much and broil the bread before the step of melting the cheese over the mushrooms. Made a second batch with shiitake mushrooms and it was also delicious. Thank you!!

    1. Skillful Cook Logo

      Oooh shiitakes sound wonderful! So glad you and your husband enjoyed the sandwiches!

  9. Skillful Cook Logo

    This recipe was amazing! I made it for lunch today and I will definitely be making this a part of my weekly routine.

  10. Skillful Cook Logo

    Made this tonight and it was soooooo good!!
    Thank you for this, a great alternative to beef.

  11. Skillful Cook Logo

    Made a special stop at the grocery store to get the ingredients and made this tonight. So freaking delicious!

  12. Skillful Cook Logo

    Made these last night and they were AMAZING! My husband, who has to have meat with every meal, inhaled them and said we need to have them again soon! I agree, I didn’t have enough mushrooms but I will totally make again and again! Everything I’ve made from your site have been delicious! Great Recipe! Thank you!

    1. Skillful Cook Logo

      you can try a light salting of the mushrooms, it will draw the moister out and they will reduce more.

  13. Skillful Cook Logo

    This is honestly one of the best sandwiches I’ve ever had in my life. All of the flavor you could dream of but none of the heavy meat feelings.

  14. Skillful Cook Logo

    I never saw this on the menu at the local Italian restaurant when I was growing up in Brooklyn. We had meatball Parmesan sandwiches, baked ziti, baked lasagna, spaghetti and meatballs, eggplant Parmesan subs, and garlic knots. But I don’t recall seeing portobello mushroom Parmesan sandwiches. This certainly looks good and gives someone a like to think about in making a homemade portobello mushroom Parmesan sandwich with tomato sauce. Certainly looks delicious to me! 🙂

    1. Skillful Cook Logo

      We love where you’re going with the mushroom parm sandwich idea! If you give this one a try, we hope you love it!

  15. Skillful Cook Logo

    I made this for dinner tonight. Just delicious….I heard audible yum sounds from my husband as he ate.

  16. Skillful Cook Logo

    Made this for lunch today! That jus was jus-t perfect. OMG I can’t want to make it again. The mushrooms are incredibly delicious!!!

  17. Skillful Cook Logo

    This is now my most favorite recipe on Skillful Cook (which is a huge statement given the fact I was basically the Falafel-Veggie-Naanwich Ambassador and practically handed that recipe out as flyers to anyone and everyone). SO flavorful and easy! 5-stars is an understatement!

  18. Skillful Cook Logo

    I made this tonight, and it was delicious! I cut the portobello into wider strips and used more mushrooms, as per the other comments. The horseradish aioli was a nice addition too!

  19. Skillful Cook Logo

    OH MY GOSH. I’m an omnivore and this was hands down the best French dip sandwich I’ve ever had! Made it for dinner tonight and it was absolutely SCRUMPTIOUS! Perfectly savory, creamy, just straight-up delicious! Thanks for a great recipe!