Layers of roasty mushrooms, havarti, lemony arugula, and an easy homemade horseradish aioli make this mushroom sandwich a WINNER. A saucy, salty, hefty masterpiece!
This is so incredibly good! I made it twice in three days. My husband asked where I got the recipe (which he never does).
In This Post
- Take Me to The Recipe
- Why I Love This Recipe
- Visual Walk-Through of the Recipe
- Video
- Frequently Asked Questions
- Ratings
The Mushroom Sandwich That I Can’t Quit
Do I always talk about Ang or do I always talk about Ang?
Really, all my favorite food ideas come from Ang. Texas-style chili, chicken wraps, and the famous tortellini soup.
I got a text a few weeks ago from Ang with a photo of her sandwich – like friends do – which was layers of roast beef, arugula, havarti, and horseradish aioli on the caramelized onion focaccia from Trader Joe’s. I spent at least 10 minutes just zoomed in on the photo, examining every saucy detail. Then I went and immediately made one for myself.
I was feeling called to a no-beef-but-still-beefy mushroom version, and it is beyond.
That horseradish aioli is pulled from the old fave portobello French dip recipe (5 stars, so good), and the roasty mushrooms, havarti, and arugula create layers of flavor that were just meant to be together. It might be over the top, but I also like a shmear of pesto rosso on the bottom of the focaccia so you can get a little brightness from tomatoes in the mix.
Please go sink your teeth into this smushy, saucy, salty and hefty masterpiece. It is a good one.
Watch How To Make This Recipe
How To Make This Mushroom Sandwich
1
Roast the mushrooms.
Toss the mushrooms with olive oil and a hefty sprinkle of seasoning (I use Cajun seasoning). Roast ’em up till they’re golden, chewy, and delicious.
2
Make that horseradish sauce.
Oh man, it’s so good. Mix your mayo, garlic, lemon, and horseradish together. Season with salt.
3
Toast and split the bread.
Would highly recommend the caramelized onion focaccia from Trader Joe’s for this one.
4
Layer your sandwich.
My layers: pesto rosso (also from Trader Joe’s, and optional), mushrooms, havarti cheese (melted for funs), arugula, and horseradish sauce on top.
5
You’re Done! Yum.
Devour and enjoy.
Frequently Asked Questions About This Sandwich
Can you make this sandwich vegan?
Yes! You would need to make the following changes: omit the cheese or switch to a plant-based cheese, use a different bread (this bread has cheese), and use a vegan mayo instead of regular.
Could I make this with meat?
Yes – as I mentioned, my friend Ang originally made a similar sandwich using roast beef. So that’s what I’d opt for if you want to skip the mushrooms!
What other bread would you recommend if I can’t access the Trader Joe’s focaccia?
A plain focaccia would still be delicious, or some fresh-sliced sourdough bread. If you want that onion flavor still, I would add caramelized onions to the sandwich too. Yum!
Could I use a different seasoning than Cajun seasoning?
Sure! You could use just about anything, even just some garlic/onion powder and salt and pepper.
Where do you buy pesto rosso?
I can usually find it at ALDI and Trader Joe’s. Target also sells a red pesto that would work! This tomato and calabrian chile spread would also be FAB. (affiliate links)
Could I sauté the mushrooms instead of roasting?
Yes, but they will retain more moisture than roasting does, so I would pour off some of the liquid as you cook so that they don’t soak the bread.
What type of mushroom is best for this sandwich?
Portobello mushrooms are my pick for this sandwich! They’re the perfect thickness and so, so delicious.
Other Ways To Use That Cajun Seasoning
Description
Layers of roasty mushrooms, havarti, lemony arugula, and an easy homemade horseradish aioli make this mushroom sandwich a WINNER. A saucy, salty, hefty masterpiece!
Instructions
- Roast the mushrooms: Preheat the oven to 450 degrees. Toss the sliced mushrooms with the avocado oil and the seasoning on a sheet pan until well-combined. Roast for 20-25 minutes, until golden brown.
- Make the horseradish aioli: Mix all the sauce ingredients in a bowl until well-combined. Taste and season.
- Assemble the sandwiches: Toast the bread for the last few minutes on the pan with the mushrooms. Split the bread, spread with pesto rosso, roasty mushrooms, havarti (pop it in the oven again for a minute if you want it to melt), arugula, and the top piece of bread shmeared with the horseradish sauce. OH MY WORD can you even? This is so good.
