These 30 minute portobello mushroom sandwiches are simple to make, juicy and delicious. They are made with succulent roasted portobello caps, and traditional burger toppings like lettuce, tomato, onion and pickles. Both meat-eaters and vegetarians will love this Portobello Mushroom Burger recipe!

portobello mushroom cap burgers with sandwich toppings on a bun

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Why We Love This Portobello Mushroom Sandwich Recipe

Do you ever get in those moods when all you want is a good meaty sandwich, but you don’t quite want an actual burger? Maybe you’re trying to encorporated more plant-based meals into your weekly menu, or maybe you’re already fully vegan. Well if you can relate, this portobello mushroom sandwich is definitely the recipe for you!

In the past, I’ve made “meaty” plant-based dishes by incorporating roasted portobello mushrooms and even sauteed portobellos as a replacement for meat, so I figured we should slap them on a sandwich and enjoy them as a plant-based burger! There are so many reasons to love this recipe, but I’ll share just a few…

  • They’re made in the oven so they can be made at any time of year, including when it is too cold to grill.
  • They are meatless and vegan-friendly!
  • These sandwiches can be customized with your favorite toppings.
  • Portobello mushrooms are low in saturated fat, but juicy and “meaty” tasting.
  • Mushrooms may have anti-aging properties and promote gut and brain health.

Honestly, what’s not to love? 

Key Ingredients

ingredients to make portobello mushroom sandwiches

Portobello Mushrooms

Search in the bulk bin for the freshest mushrooms. You’ll be able to tell if they’re fresh if the gills are covered by a paper-thin layer of white cap. Ideally, they’ll be mildly damp and springy, and absolutely not mushy, dried out, or too moist. 

Burger Sauce

We like Sir Kensington Special Sauce for these sandwiches. There are other burger sauces on the market including large national brands like Hellmans and Heinz. You can also find vegan and Whole30 compliant versions of burger sauce. Find them in the condiment section near the mayonnaise. You can also make your own burger sauce! 

Tamari or Soy Sauce

Both tamari and soy sauce work for this recipe. We all know and love soy sauce, but tamari is a wheat-free version that has a smoother consistency and richer taste.

Burger Toppings

Add your favorite burger toppings, including lettuce (or arugula) tomato, red onion rings, and dill pickle chips. Feel free to add any additional toppings that align with your preferences.

Step By Step Instructions To Make These Portobello Sandwiches

prep and roast the mushrooms

Step 1: Prepare the Mushrooms

Preheat the oven to 400 degrees F and brush the insides and outside of the mushrooms with oil and soy sauce (or tamari). Season with pepper and then arrange the mushrooms, gill side up, on a baking sheet. 

Step 2: Roast Mushrooms

Roast the mushrooms until they’re tender and beginning to brown, which should take about 15 minutes. Flip the mushrooms and discard any accumulated juices, and then roast again until the mushrooms are brown and slightly dry, which would take about 5 minutes more. 

smear burger sauce on the buns before adding the mushroom and toppings

Step 3: Prepare Burger Buns

Lay out your rolls and cut them side up on your work surface. Spread the burger sauce over the buns, dividing evenly. Place your lettuce on the bottom bun. 

Step 4: Compile Portobello Burgers

Top the lettuce with your roasted portobello, tomato, onion, and pickle chips. Top each sandwich with a roll top and serve immediately. 

a single portobello mushroom sandwich loaded with toppings and burger sauce

FAQs and Expert Tips

How can I make this recipe vegan?

To make this recipe vegan, substitute Vegan Burger Sauce or Vegan Mayonnaise for the burger sauce.

Can the portobello mushrooms be grilled?

Yes, grill them over medium heat, gill-side-up first. They are ready to flip once they are lightly brownes and the liquid pools in the cap. Then, flip them to drain the liquid and grill the other side for 1 to 2 minutes.

How can I make burger sauce from scratch?

Make your own burger sauce by using ¼ cup mayonnaise, 2 tablespoons ketchup, 1 teaspoon yellow mustard, 1 teaspoon relish, 1 teaspoon lemon juice or white vinegar, 1/8 teaspoon garlic powder, and a pinch each celery salt and pepper. Whisk all of the ingredients well, and use this mixture in place of store-bought sauce.  

Make Ahead

Your portobellos can be roasted up to three days ahead. Re-warm them in the microwave for 30 seconds per cap, or until they’re steaming hot before assembling the sandwiches.

Substitutions and Variations

  • Instead of the burger toppings and sauce suggested here, get creative with other toppings. Try arugula, sun dried tomato and pesto or roasted red peppers, sprouts and avocado with truffle or garlic aioli.
  • Melt fresh mozzarella, provolone or cheddar on the portobello in the last few minutes of roasting for a cheese (portobello) burger!
  • Make the recipe vegan by subbing in vegan burger sauce, vegan mayonnaise or guacamole.

Additional Mushroom Recipes To Try

Thanks so much for reading! If you are new here, you may want to sign up for my email newsletter to get a free weekly menu plan and the latest recipes right to your inbox. If you make this recipe, please come back and leave a star rating and review. I would love to hear what you thought!

Happy Cooking! ~Katie

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portobello mushroom sandwich with toppings on a bun

Portobello Mushroom Sandwich

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5 from 5 reviews

  • Author: Katie Webster
  • Total Time: 30 mins
  • Yield: 4 Sandwiches 1x
  • Diet: Vegetarian
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Description

These 30-minute portobello mushroom sandwiches are simple to make, juicy and delicious. They are made with succulent roasted portobello caps, and traditional burger toppings like lettuce, tomato, onion and pickles. Everyone will love this Portobello Mushroom Burger Sandwich!

Ingredients

Scale

For The Mushrooms:

4 large portobello mushrooms, stems removed and gills scraped out

1 tablespoon extra-virgin olive oil

1 tablespoon soy sauce or tamari

Freshly ground pepper, to taste

For The Sandwiches:

4 kaiser rolls or sandwich rolls, split and toasted

8 tablespoons Burger Sauce or Special Sauce, see ingredient note

4 leaves green leaf lettuce or 1 1/2 cup arugula

1 medium tomato, cored sliced

2 slices red onion, broken into rings

12 dill pickle chips

Instructions

  1. Prepare Mushrooms: Preheat oven to 400 degrees F. Brush insides and outsides of mushrooms with oil and soy sauce. Season with pepper. Arrange mushrooms, gill side up, on a baking sheet.
  2. Roast the mushrooms until tender and beginning to brown, about 15 minutes. Flip mushrooms, discard any accumulated juices, and roast until mushrooms are brown and slightly dry, about 5 minutes more.
  3. Meanwhile, lay rolls, cut side up on work surface. Spread burger sauce over the buns, dividing evenly. Place the lettuce on the bottom bun. 
  4. Top the lettuce with the portobello. Top with tomato, onion and pickle chips, dividing evenly. Top each sandwich with the roll tops and serve immediately.

Notes

Ingredient Note: We like Sir Kensington Special Sauce for these sandwiches. There are other burger sauces on the market including large national brands like Hellmans and Heinz. Find them in the condiment section near the mayonnaise. You can also make your own using ¼ cup mayonnaise, 2 tablespoons ketchup, 1 teaspoon yellow mustard, 1 teaspoon relish, 1 teaspoon lemon juice or white vinegar, 1/8 teaspoon garlic powder, and a pinch each celery salt and pepper. Whisk it well and use in place of the store-bought sauce.  

Tip: To Make this recipe vegan, substitute Vegan Burger Sauce or  Vegan Mayonnaise for the burger sauce.

Make Ahead: Portobellos can be roasted up to three days ahead. Re-warm in the microwave for 30 seconds per cap, or until steaming hot before assembling sandwiches.

  • Prep Time: 5 mins
  • Active Time: 15 mins
  • Cook Time: 20 mins
  • Category: Main Course
  • Method: Oven
  • Cuisine: American

Nutrition

  • Serving Size: 1 Sandwich
  • Calories: 395 cals
  • Sugar: 4 g
  • Fat: 19 g
  • Carbohydrates: 46 g
  • Fiber: 4 g
  • Protein: 10 g

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