Vegan Portobello Mushroom Burger

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This vegan portobello mushroom burger is piquant and scrumptious at the same time. Grilled portobello mushroom caps are seasoned with a fajita spice mix, then layered among guacamole, salsa, vegan nacho cheese sauce, and spicy fajita veggies.

A burger with ketchup, lettuce, yellow cheese sauce, bell peppers, guacamole and grilled mushroom cap on brown paper. French fries are placed next to it.

This mushroom burger recipe was inspired by our vegan portobello mushroom fajitas. It is rich, colorful, and full of flavors. If you also love Tex-Mex food try our classic vegan bean chili, our quinoa sweet potato chili, our vegan taco soup, or our Mexican vegan rice casserole recipes.

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What can you expect?
Ingredients
Instructions
Cooking tips
Variations
Serving ideas
Storing tips
FAQs
More vegan burger recipes
Vegan Portobello Mushroom Burger

What can you expect?

If you’ve never eaten it before, then you are in for a treat. In this burger recipe, you marinate and grill large portobello mushroom caps in whole and use them as burger patties.

Obviously, it is something different from a classic beef burger. If you looking for a beefy texture, try our TVP burger or tofu burger.

This grilled portobello mushroom burger…

is piquant and creamy at the same time.
is full of rich and colorful ingredients.
has a charred flavor and a meaty texture.
is healthier than beef burgers.
is easy to make and incredibly tasty.

A hand is holding a burger with ketchup, lettuce, yellow cheese sauce, bell peppers, guacamole and grilled mushroom cap on brown paper. French fries are placed next to it.

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Ingredients

To build this vegan portobello mushroom burger, here is what you need:

Large portobello mushroom caps → marinated in fajita spice mix, garlic, lime, sweet smoked paprika powder, salt, black pepper, and olive oil
Lettuce leaves
Fajita veggies → We have a recipe for an easy sheet pan version where you can make a large batch in one go.
Guacamole
Salsa
Nut-free vegan nacho cheese sauce
Burger bun

🛒 You can find detailed measurements for all ingredients in the printable version of the recipe card at the bottom of this post.

Instructions

Marinating portobellos

Take a small-sized bowl
Add olive oil, salt, black pepper, minced garlic cloves, freshly squeezed lime juice, fajita spice mix, and smoked sweet paprika powder.
Stir until they are thoroughly combined.

Glass bowl with oil and different colored spices from brown to red.

Peel portobello mushroom caps with a sharp knife and take out the stems.
Take a glass bowl (the one in the photo is also our meal prep bowl) and place the mushroom caps in it. If you make multiple servings, choose a bowl that would fit them in one layer.
Pour the marinade on top of them. Use a silicone brush to spread the marinade. Toss and turn a couple of times, to make sure they are covered everywhere.
Repeat this step once more after an hour or in the morning if you marinate them overnight to make sure mushrooms are not getting dry. In the end, it will look like the ones in the below photo.

Two large mushroom caps marinating in an oil spice mix in a glass container.

Pan-frying

The easiest way is if you have a grill pan and you cook them on a stovetop.

Preheat the grill pan over medium heat.
Once it is sizzling hot, place the marinated mushroom caps on it. No need to add extra oil since the marinade already contains enough.
Gently push the mushrooms down for a few seconds on each side with a spatula to allow the greater surface of the mushrooms to be grilled.
Brush each side with the leftover marinade once.
Cover the grill pan to allow hot air to circulate through the pan (just as it would in a real gas grill) and cook both sides for approx. 5 minutes each. That is all! You can see how they look when they are ready in the below picture.

Two large mushroom caps in a grill pan with crispy charcoal lines.

Building a vegan portobello mushroom burger

The best part of the whole recipe is building your yummy portobello burger. I know that the more layers you add, the harder it is to eat. However, I really-really recommend all these layers for you to try. They are absolutely amazing and delicious together!

I started off with a toasted bun.
First up is a generous spread of salsa sauce. Mild or hot depending on your preference.
Add green leaf lettuce because the ruffles look so pretty.
Next up is some spicy, veggie-packed nut-free vegan nacho cheese sauce.
Then, add a handful of fajita veggies, aka roasted bell peppers and red onions.
Now comes the star of this burger the grilled portobello mushroom caps.
Finish it off, we some homemade guacamole.

What else can you add? To take it even further, we love to add another layer of grilled mushroom caps below the cheese sauce! So tasty and filling! And look how beautiful the layers are below! You can also add tomato slices instead or on top of the salsa. Or avocado slices instead of guacamole.

Cooking tips

How long? – Mushrooms have a spongy texture. Therefore, the longer they soak in the marinade, the more intense the flavor will be as they absorb more. We recommend overnight soaking, but 2 hours should be the bare minimum to get them seasoned properly.
How much? – You don’t need to make a lot of marinades as you don’t need to immerse the mushroom caps in it. We do flip them or brush them a couple of times.
Hot or sweet? – In case you prepare the burger for kids or for people who don’t like spicy food, you can skip the hot chili powder and add more sweet smoked paprika powder.
Powder vs fresh ingredients? – We like using fresh ingredients if we have them, but you can use onion powder or garlic powder instead.

Variations

Baking – You can use a glass oven-safe dish or a grill pan (provided that the handle is not made of plastic). Preheat the oven to 400 Fahrenheit (ca. 204 °C) and grill them under the broiler for 10 minutes, turning them at halftime.

On a gas grill – Our little trick to grilling mushrooms is to use aluminum foil drip pans. Preheat your gas grill to 400 Fahrenheit (ca. 204 °C) and grill the marinated portobello mushroom caps for 10 minutes, turning them at halftime.

Serving ideas

Choose classic French fries for a classic burger and fries combo. Or, try sweet potato wedges or roasted potatoes.
Serve your burger alongside roasted cauliflower, grilled vegetable kabobs, or other vegetables.
Rice, quinoa, or riced sweet potatoes are all excellent side dishes that pair well with these vegan portobello mushroom burgers. Try making cilantro lime rice from our copycat Chipotle veggie bowl recipe for an extra burst of flavor.

A burger from above with the top bun put on the side. Grilled charcoaled mushroom cap is on the top with lettuce, yellow and red sauce and red pepper slices below it.

Storing tips

In the fridge: You can store raw portobello mushrooms easily up to a week in the fridge, or at room temperature for 1-2 days. As for grilled mushrooms, they lasts for 3-4 days without any problem. We recommend assembling the burger before serving and not storing them as complete burgers.

In the freezer: Raw mushrooms are not recommended, but you can absolutely freeze grilled portobello.

Reheating: We recommend using a grill pan to refresh them after thawing.

FAQs

How does a portobello mushroom burger taste like?

All mushrooms have this spongy texture which help them to soak up marinades perfectly, especially when heat is involved. You can season them with strong spices, so they will be flavorful. When you are biting in a mushroom burger, you will feel a chewy, meaty texture.