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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!
Karen
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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.
It is wonderful, it is meatless, it is the epitome of comfort food.
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
You can use vegan Worcestershire sauce or substitute soy sauce.
You could add a little bit of water instead.
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.
Portobello French Dip with Horseradish Aioli
- Total Time: 45 minutes
- Yield: 4 mega sandwiches 1x
Description
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.
Ingredients
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
Instructions
- Roast the Mushrooms: Preheat oven to 450 degrees. Toss mushroom slices with oil and seasoning. Roast for 20-30 minutes.
- 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.
- 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.
- 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).
- 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.
Equipment
Buy Now → 
Buy Now → 
Buy Now → - 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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This is THE best dinner ever. We have had this several times and again tonight. Cannot wait!
These sandwiches are on our favourite recipe list and I make them frequently! Only thing I notice is it takes much longer than 20 to get the onions where you want them and I always double the mushrooms because they shrink a lot.
These are SO good. Seriously phenomenal. You won’t miss the meat at all. I think these are better than a traditional French dip. My meat-lovin’ hubby agrees too!
I love ALL your recipes, but this French Dip recipe here is basically a religious experience. It is BEYOND GOOD!!! Thank you so much.
They look so fun and easy to make, and I bet they taste amazing. I’m going to try them with my kids this weekend. They will love them!
I made this tonight and it was soooo good! I added some lion’s mane mushrooms as well but the rest was as written. So meaty and the jus was just perfect. Thanks so much!
This recipe is amazing! I love the combination of ingredients and flavors!
I made these sandwiches tonight and loved them. The deli counter at my grocery store sells a horseradish cheddar, which is my favorite go-to for roast beef sandwiches. So, I did omit the horseradish mayo and replaced the provolone with the horseradish cheddar. The flavors were definitely still there though!
I definitely will be making them again!
Really yummy sandwich.
I just made this and it’s incredible!
SO delicious! Even my teenage boys who are against plant based meals liked it and said it really tastes like French dip.
I am curious about the protein value. The nutrition facts state that one serving has 19 grams of protein. Is that correct? If so where is the protein from?
Deeeeelicious! The horseradish aioli takes this one to the next level. I used frozen old hoagie and it was still incredible. 😆
I don’t think I’ve ever left a recipe review, but this one really deserves the 5 stars! I’ve made this so many times over the years and it’s never done me wrong. Especially as a vegetarian who used to love French Dips and roast beef. 10/10 will make again and again
I’m making my way through your recipes that have mushrooms in them and this one was amazing!!! The combination of flavors was just so, so yum.
Looking for the recipe that was on instagram yesterday somewhat similar but not the same….
It’s coming next week! 🙂
This was incredibly delicious! Made just as described. The whole family loved it and I can’t wait to make it again!
These are SOOOO good and have become a part of our regular dinner rotation!!
Made these last night and they were so good! We love french dips but have been trying to cut down on meat a few times per week – this is the perfect recipe for a meat-loving (but aspiring to be healthier) family! Thank you!
Pleaaaaaaaaaaaaase do yourself a favor and make this sandwich! It is in our weekly rotation and we can’t get enough of it. Thank you so much for all you do, Lindsay and team! 10 stars!
Soooooooo good! I get the onions going first since I like them super caramelized while I prep everything else. I threw a few sprigs of fresh thyme for the au jus.
These are amazing! We had them for dinner the other night and my boyfriend, who is not a vegetarian like me, absolutely loved them. I’m just wondering why they are so high in fat & sodium, and is there a way to cut back on that? I’m asking because I want to eat this sandwich as often as possible!
Holy moly! SO INCREDIBLE. I will say, next time, I’ll double the portobellos. They reduce so much in roasting. It was so delicious I can’t be mad. Nice work y’all.
Excited to try this. It looks delicious but also easy and fast to make. Mushrooms can be such a great meat substitute especially when paired with sourdough.
We’ve made this one twice now and really like it! Great vegetarian meal… I think I actually prefer this to a traditional French dip!
Hey Lindsay, I’m not into vegetarian meals however this Portobello roll/burger/sandwich is fantastic. I made my own steak seasoning. The horseradish makes it all come together. Great work.
So glad you enjoyed it, Shannon! Thanks so much for the review!