Portobello Mushroom Sandwiches are quick to make with marinated mushrooms, sautéed peppers and shallots, provolone cheese, and a generous spread of basil aioli.
Serve with Lemon Roasted Potatoes, a crisp green salad, or Tomato Orzo Pasta Salad.
Easy Mushroom Sandwiches
Everything in this portobello sandwich works together—the meaty texture of the mushrooms, the tangy marinade, the gooey provolone, and that punchy basil aioli. It’s hearty without being heavy and makes a good plant-based alternative to burgers.
The mushrooms soak up all the savory flavor from the balsamic-Worcestershire mixture while the bell peppers and shallots soften and lightly caramelize in the skillet. Melting the cheese directly over the warm filling helps hold everything together. Pile it all onto toasted sub rolls and you’ve got a crave-worthy sandwich that’s easy to make in minutes.
Ingredients for Portobello Mushroom Sandwiches
You will need the following:
- Mayonnaise – The base for the basil aioli.
- Fresh Basil – Chopped before blending for even texture and better distribution. Use packed leaves with stems removed for the best result.
- Garlic – Adds sharpness and depth to both the aioli and the cooked veggies. A little goes a long way.
- Lemon Juice + Zest – Brings acidity and balance to the aioli. The zest adds a little extra punch.
- Olive Oil – Helps the marinade coat everything evenly before cooking.
- Balsamic Vinegar + Vegan Worcestershire Sauce – For a rich, tangy flavor to the marinade. Check the label on your Worcestershire—many brands aren’t vegetarian, but there are plant-based Worcestershire sauces that work just as well.
- Seasonings – Garlic and onion powders, salt, and pepper add savory flavor without overpowering the vegetables.
- Mushrooms – Large portobello caps were used for this recipe, but you could easily substitute an equivalent amount of cremini mushrooms.
- Green Bell Pepper – Use green or red peppers for a little crunch and sweetness to balance the richness of the mushrooms and cheese.
- Shallot – Use thin slices so they caramelize a bit in the pan.
- Butter – For sautéing the vegetables; olive oil works too.
- Provolone Cheese – Mozzarella, Havarti, and Gouda also pair well with the marinated mushrooms.
- Sub Rolls – Choose rolls that are sturdy enough to hold up to the filling but still soft inside. Lightly toasting them adds just the right texture.
How to Make Portobello Mushroom Sandwiches
STEP ONE: Make the Basil Aioli. Add mayonnaise and chopped basil to a food processor. Blend for about 30 seconds, until smooth and green. Add minced garlic, lemon juice, and zest, and pulse again until combined. Set aside.
STEP TWO: Make the Marinade. Whisk together olive oil, balsamic vinegar, Worcestershire, garlic powder, onion powder, salt, and pepper in a small bowl.
STEP THREE: Marinate the Veggies. Place sliced mushrooms, bell pepper, and shallots in a large bowl. Pour the marinade over and toss to coat. Let it sit while you prepare the skillet.
STEP FOUR: Cook the Vegetables. Set a large skillet over medium-high heat and add butter. Once melted, add the marinated vegetables (discard leftover marinade). Cook for 7–9 minutes, stirring often, until everything is tender and browned.
STEP FIVE: Melt the Cheese. Divide the mushroom mixture into two portions in the skillet. Top each with a slice of provolone. Cook for 1–2 more minutes, until the cheese is melted. Remove from heat.
STEP SIX: Toast the Rolls and Assemble. Set the rolls under a low broiler to lightly toast. Once ready, spread both sides with basil aioli. Add the cheesy mushroom mixture, sprinkle with parsley, and serve warm.
Make It Vegan 🌱
- For plant-based sandwiches, use egg-free mayo and dairy-free provolone cheese. Everything else is already vegan.
Storage
- The cooked mushroom filling is best served fresh. Leftover basil aioli can be stored in an airtight container in the refrigerator for several days—try it on Caprese Burgers!
More Recipes You’ll Love!
- White Bean Burgers
- Mushroom Po’ Boy Sandwiches
- Spinach Stuffed Portobello Mushrooms
- Mozzarella Stuffed Mushrooms
- Vegan Philly Cheesesteak
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Portobello Mushroom Sandwich Recipe
Ingredients
For the Basil Aioli:
- 1 cup mayonnaise
- 2/3 cup fresh basil leaves chopped
- 2 teaspoons garlic minced
- 1 tablespoon lemon juice
- 1 teaspoon lemon zest chopped
For the Marinade:
- 1 tablespoon olive oil
- 3 tablespoons balsamic vinegar
- 3 tablespoons vegan Worcestershire sauce
- 1/2 teaspoon garlic powder
- 1/2 teaspoon onion powder
- 1/2 teaspoon kosher salt
- 1/2 teaspoon ground black pepper
For the Sandwiches:
- 2 large portobello mushroom caps destemmed and thinly sliced
- 1 green bell pepper deseeded and sliced
- 1/4 cup shallot thinly sliced
- 1 tablespoon butter
- 2 sub rolls
- 2 slices provolone cheese
Instructions
- Add mayonnaise and chopped basil to a food processor. Blend for about 30 seconds, until smooth and green. Add minced garlic, lemon juice, and zest, and pulse again until combined. Set aside.
- Whisk together olive oil, balsamic vinegar, Worcestershire, garlic powder, onion powder, salt, and pepper in a small bowl.
- Place sliced mushrooms, bell pepper, and shallots in a large bowl. Pour the marinade over and toss to coat. Let it sit while you prepare the skillet.
- Set a large skillet over medium-high heat and add butter. Once melted, add the marinated vegetables (discard leftover marinade). Cook for 7–9 minutes, stirring often, until everything is tender and browned.
- Divide the mushroom mixture into two portions in the skillet. Top each with a slice of provolone. Cook for 1–2 more minutes, until the cheese is melted. Remove from heat.
- Set the rolls under a low broiler to lightly toast. Once ready, spread both sides with basil aioli. Add the cheesy mushroom mixture, sprinkle with parsley, and serve warm.
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