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.

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.

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.

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

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.

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.

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:

• While the garlic aioli is wonderful on these burgers, you’ll also like them with a drizzle of Green Goddess dressing or easy red bell pepper aioli (both pictured below).
• Slices of ripe tomato (heirloom variety if you can get them).
• Grilled red peppers in place of roasted.
• Thin slices of English cucumber or Quick pickled cucumbers.
• Pink pickled onion or kimchi in place of grilled onions.
• A sprinkle of sliced black olives or a black olive tapenade in place of the aioli.

FAQ’s

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 veggie burgers and sandwiches?

• Vegan Lentil Burgers with Mushrooms Spinach and Quinoa From Dawn at Girl Heart Food.
• Cornmeal Crusted Veggie Burgers here at Garlic & Zest.
• Southwestern Sweet Potato Quinoa Burger via Dana at Killing Thyme.
• Chickpea and Brown Rice Burger via Carmy at Carmy Run Eat Travel.
• Carrot Tahini Quinoa Veggie Burger with Tzatziki and Purple Slaw from Tricia at Rhubarbarians.

More portobello and mushroom recipes:

• Turkey Taco Stuffed Mushrooms
• Mushroom Lasagna
• Kale, Barley Mushroom Gratin
• Balsamic Dijon Roasted Mushrooms
• Cheesy Spinach Stuffed Mushrooms
• Savory Mushroom Tartlets
• Wild Mushroom and Leek Crostini

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