Grilled Portobello Mushroom Burger

If you like mushrooms, you’ll love this grilled portobello mushroom burger. It’s a quick and easy recipe that makes a flavorful, satisfying portabello mushroom sandwich that’s perfect for a healthier lunch or dinner. We top ours with sweet roasted bell peppers, melty provolone cheese and a tasty garlic aioli. Vegetarians and meat eaters alike, crave this portobello burger.

This post has been updated for recipe, photos and content since its original publication in 2014.

Portobello mushroom caps on a cutting board.

What are portobello mushrooms?

Portobellos (a.k.a. Agaricus Bisporus) are actually the same as white button mushrooms AND cremini mushrooms, they’ve just been allowed to grow into their full-fledged, burger mimicking selves. This Mashed article goes into greater detail on the difference between Portobellos, white mushrooms and creminis.

What is a portobello mushroom burger?

At its core, a portobello burger is a vegetarian sandwich — and a good one.

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Unlike other veggie burgers, which require mixing with other ingredients and forming into patties, portobello mushrooms, already have the look and shape of burgers, making them a quick and easy swap for a meat patty.

Additionally, mushrooms have a meaty, toothsome quality as well as a rich umami flavor that while not exactly mimicking meat, makes a fine stand-in for a beef burger for anyone looking to add more vegetables into their diet or just eat a bit healthier.

For these portobello burgers we’re starting with big ‘shrooms that will easily fill a bun and adding a simple, but really flavorful rub along with a host of traditional (and a few out of the ordinary) burger toppings.

the spice mix for seasoning the portobello burgers.

Before we get to the portobello mushroom burger, let’s start with the seasoning.

This simple garlic and herb rub is the punch of flavor that takes this from a plain portabello mushroom sandwich to a portobello burger that’s worthy of a backyard cookout. It’s fresh and herbal with enough spice and kick to put a smile on your face.

To season the mushroom burger, I use a garlicky herb and spice rub instead of a marinade. I find that a zippy rub seasons the flesh of the mushroom without weighing it down with excess oil or other liquids.

Ingredients for the portobello mushroom burger

  • Large Portobello Mushroom Caps
  • Garlic
  • Fresh Thyme
  • Fresh Tarragon
  • Fresh Rosemary
  • Crushed Red Pepper
  • Kosher Salt
  • Black Pepper
  • Provolone Cheese Slices (or other melty cheese)
  • Roasted Red Peppers
  • Red Onions
  • Micro Greens (optional)
  • Garlic Aioli (optional)
  • Whole Wheat Buns
Prepping the portobello mushrooms by removing the gills and seasoning with the garlic herb rub.

How to clean a portobello mushroom cap

“Cleaning” a portobello mushroom is a misnomer. It’s not like you’re going to run the fungi under a faucet or soak them in a bowl of water. You’d never want to do that.

Why? Mushrooms are like sponges and will absorb any liquids that you add to them.

Consequently, if you submerge them in a water, they will absorb the liquid and rather than grilling, the fungi will steam when you cook them.

  1. To “clean” the mushrooms, wet a paper towel with water and squeeze out the excess.
  2. Then gently brush any dirt or debris from the mushroom caps with the damp paper towel.
  3. Use your fingers or a sharp knife to remove the stem (or just trim the tip of the stem with a knife, as the stems are edible).
  4. With a teaspoon, scrape away the mushroom gills (shown in the photo above) and discard.

Do you need to remove the gills from the portobello mushrooms?

The gills are edible, so technically, you don’t have to remove them. However, the gills tend to give the mushroom (and anything that touches it) a muddy appearance and most cooks remove them for aesthetic reasons.

Grilling the seasoned portobello mushrooms and red onions.

Should I marinate the portobello mushrooms?

As I said before, mushrooms absorb liquids like a sponge, so soaking a portobello cap in an actual marinade would overpower the naturally mellow, earthy flavors of the fungi.

My solution is to lightly brush the mushroom caps with olive oil (use a pastry brush) and sprinkle on a simple garlic herb seasoning, so that they get the flavor without being weighed down by an oily marinade.

I usually clean and prep the portobello burgers and ready the other ingredients at the same time as my hubby is preheating the grill.

the portobello burgers with melted cheese and toasted whole wheat buns on a rimmed baking sheet.

To make these veggie burgers feel and taste like the occasion they are, you need to pile them with tasty, eye-popping toppings. Here’s what I choose for this recipe, but I’ve got other ideas for you further down in the post.

  • Sweet Roasted Bell Peppers (I used red, orange and yellow) I like roasted peppers that have the skins peeled, because they’re easy to eat and their sweetness pairs well with the mushrooms.
  • Grilled Red Onions — we like them grilled because the flavor is softer and less intense.
  • Sliced Cheese (we like provolone, muenster, swiss or smoked gouda but any good melting cheese works here.)
  • Fresh Micro Greens (like baby arugula or kale have a fresh intensity that really accentuate the flavors in the veggie burger.
  • Garlic Aioli (this homemade mayonnaise is rich & thick with a punchy taste of garlic that will have you licking your fingers).
  • Lightly Grilled Whole Wheat Sandwich Rolls – We like whole wheat for the increased nutrition and nutty flavor. In addition, they tend to hold up to the mushroom burgers and toppings better than a typical brioche bun.

Grilling portobello mushroom burgers

  1. Grill the portobello mushrooms on a preheated grill (about 375°-400° F) for 8-10 minutes, flipping halfway through, until the mushrooms are tender.
  2. Add the cheese after flipping the mushrooms so the cheese will melt as the portobello mushroom caps finish grilling. (We like to add the cheese to the bottom of the ‘shrooms after flipping, so they’re cupped inside and you don’t lose any cheesy goodness.)
  3. Grill the red onions at the same time as the mushrooms. Grilling the onion makes them more tender and adds a smoky char which we like.
  4. Once the portobellos and onions are done, transfer them to a rimmed baking sheet and assemble the burgers with the other ingredients.

What to serve with portobello mushroom burgers

We love to stack our portobello burgers with a variety of colorful vegetables and a flavorful sauce or spread.

For these grilled mushroom sandwiches, I pile on grilled red onions, roasted sweet peppers and a flurry of micro greens, but it’s also good with a leafy green lettuce.

A thick slather of garlic aioli makes these veggie burgers really pop!

Swaps and variations:

Mushroom burgers are endlessly customizable to suit your tastes. Here are some other options for topping your portobello burgers:

FAQ’s

Can I cook the portobello burgers inside?

Yes. If you don’t have an outside grill, you can certainly use a grill pan over medium high heat to cook your ‘shrooms.

Are mushroom burgers healthy?

Compared to an 80/20 beef patty? You bet they are! According to my nutrition calculator, each one of these portobello mushroom burgers has under 300 calories, even with the bun, cheese and aioli. To make them even healthier, you can skip the cheese and double up on the veggies.

Is portobello mushroom a meat substitute?

It can be. Portobellos are big and meaty with a substantial chew, making them a great swap for meat in various recipes. They also have an umami quality that makes them a natural stand-in for burgers. I’m not saying that the mushrooms taste like meat, but they certainly give you the burger vibe when you’re biting into one.

When we’re craving burgers, but want something healthier, these zesty grilled portobello mushroom sandwiches are the easy answer. They’re great for meatless Mondays and even my carnivorous husband looks forward to dinner when they’re on the menu.

To make it vegan, swap vegannaise with minced garlic for the aioli and substitute your favorite vegan cheese for the cheddar, monterey jack and gouda.

To make it gluten free: use gluten free rolls or skip the bun altogether and make it a knife and fork meal.

Craving more burgers and sandwiches?

More portobello and mushroom recipes:

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grilled portobello mushroom burgers on a plate.
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4.72 from 7 votes

Grilled Portobello Mushroom Burgers

These meaty grilled portobello burgers are one of our favorite vegetarian meals. They’re flavorful and delicious, stacked with sweet bell peppers, grilled onions, melty cheese and an irresistible garlic aioli.
Author: Lisa Lotts
Course Main Course
Cuisine American
Keyword burgers, mushrooms, vegetarian
Dietary Restrictions Vegetarian
Prep Time 35 minutes
Cook Time 10 minutes
Total Time 45 minutes
Servings 8

INGREDIENTS:

FOR SEASONING RUB:

  • 4 cloves garlic minced
  • 1 tablespoon fresh thyme leaves minced
  • 1 tablespoon fresh tarragon minced
  • teaspoons fresh rosemary minced
  • ½ teaspoon crushed red pepper flakes
  • 1 teaspoon Diamond Crystal kosher salt or 1/2 teaspoon Morton’s Kosher Salt
  • ½ teaspoon freshly ground black pepper

FOR PORTOBELLO MUSHROOM BURGERS:

  • 4 portobello mushroom caps
  • ¼ cup + 2 teaspoons olive oil
  • 2 roasted bell peppers
  • 1 red onion sliced
  • 4 slices provolone cheese or other cheese
  • ½ cup garlic aioli
  • 1 cup microgreens or 4 slices of leafy greens
  • 4 whole wheat sandwich buns

DIRECTIONS:

  • Clean the mushroom caps by brushing away the debris from the caps with a damp paper towel. Remove the stems with your fingers, or slice them off with a sharp knife and discard.
  • Use a spoon to scrape the gills from the underside of the mushroom caps. Set aside.

FOR THE SPICE RUB:

  • In a small bowl combine the garlic, thyme, tarragon, rosemary, crushed red pepper flakes, kosher salt and black pepper.
  • Brush the tops and bottoms of each mushroom cap with 1 tablespoon of the olive oil and divide the spice rub between them, rubbing it into the mushrooms (the seasoning will stick better to the underside of the fungi).
  • Brush the sliced onions with the remaining olive oil and set aside.

FOR PORTOBELLO MUSHROOM SANDWICH

  • Heat a grill to a medium high heat – about 375-400 degrees.
  • Place the mushrooms on the grill, cap side down and cook for 4-5 minutes. Grill the red onions at the same time. Flip the mushrooms and onions and cook for an additional 3-4 minutes. until the flesh is softened and exterior takes on some grill marks.
  • Top each mushroom with a slice of cheese and cook for 1-2 more minutes until the cheese is melty.
  • Split the buns in half and toast them on the grill for 1-2 minutes, until lightly browned.

ASSEMBLE THE PORTOBELLO BURGERS:

  • Spread garlic aioli on the top and bottom buns. Place mushrooms on the buns. Top with one or two slices of roasted bell peppers, grilled onions and micro greens or lettuce. Place the top bun on the mushroom burger and serve.

NUTRITION:

Calories: 258kcal | Carbohydrates: 17g | Protein: 6g | Fat: 18g | Saturated Fat: 4g | Polyunsaturated Fat: 1g | Monounsaturated Fat: 8g | Trans Fat: 0.001g | Cholesterol: 11mg | Sodium: 728mg | Potassium: 281mg | Fiber: 2g | Sugar: 3g | Vitamin A: 255IU | Vitamin C: 8mg | Calcium: 120mg | Iron: 2mg

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29 Comments

  1. 5 stars
    Amazing variations amazing sandwich

  2. 5 stars
    I made these the other night. To say it was a hit is an understatement! My husband LOVED the mushroom burger with all of the fixings. He kept raving about all of the flavors with each bite he took. I didn’t get a chance to make the garlic aioli, but the seasoned portobello was topped with cheese, roasted red peppers, sauteed onions (instead of grilled), lettuce and some plain mayo. I also topped mine with some olive tapenade and avocado – yumm! He was happy I made 4 for just the two of us so he had leftovers for lunch the next day!

  3. 5 stars
    I can’t wait to try making this (I am currently in remote Tanzania) – Just one thing, normal Worcestershire sauce containes anchovies (fish) so not suitable for this vegetarian… 🙂

  4. So many good ingredients and textures in this veggie burger. I really like your aioli,

  5. I have minced mushrooms in the past as a meat substitute so love this is idea of Portabella mushroom burgers.

  6. 5 stars
    I have never thought to use Portabella mushrooms as a substitute for a beef pattie. The carnivore in me was confused but this is absolutely delicious. Love the sauce.

    1. Mica, I completely understand — mine is a family of carnivore’s but they really enjoyed this “burger”. Just sayin’!

  7. Good for you sticking to your plan and not changing it! I do the same thing sometimes, worrying that others who are not vegetarian or veggie lovers will be disappointed if they do not have meat. These burgers look amazing!

    1. Thanks, Kim! The funny part was the girls really did love them! No complaints!

  8. I love portabella mushrooms especially as a meat replacement. I’m going to have to try your “burger”, it looks messy and delicious.

    1. Yes, it’s totally messy – the kind of sandwich you eat while hunched over a plate to catch all the drippings!

    1. I’m so glad you like them, Keith! They’re really good! Messy, but good!

  9. Mushrooms are one of my secret weapons in converting meat lovers to the vegetarian darkside so I can see why your gorgeous burgers were a huge success!

  10. foodhuntersguide says:

    what a delicious and healthy idea

    1. Thanks! It really is a delicious, satisfying dish!

  11. I love this idea. I’m a big fan of portobellos and this is the perfect alternative to beef. The addition of basil and garlic makes this burger totally spring worthy. Yum.

    1. I appreciate that Ali! Thanks so much, I’m glad you like it!

  12. There’s nothing like a homemade burgers and I totally love Portabella mushrooms! What a fun twist with the basil-garlic aioli….I can almost taste the flavors!

    1. I agree, Molly! And the best part is you don’t walk around with a food baby the rest of the day!

  13. immaculatebites says:

    Totally agree! The colors are So visually appealing , fresh and inviting – am a carnivore . However, you would not hear me complain either while eating this burger. YUM!!!

  14. Kylee Cooks says:

    Ohhhh, that aioli though! Looks so good. I bet it would pair well with pretty much anything.

    1. I’ve got some leftover — and yes, it’s good on everything!

  15. 5 stars
    I love this idea! And that tasty looking sauce just brings it all together, I will definitely be giving this a try. Thanks!

  16. Yum, yum, yum… That Basil Aioli is out of this world delicious! – And to put it on grilled mushrooms… genius! 🙂
    Can’t wait to make it at home!