Portobello Mushroom Burgers

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Portobello Mushrooms Burgers made on the grill for the perfect vegetarian burger that's healthy and ready in no time.


These easy Portobello Mushroom Burgers make the best vegetarian burgers, especially when topped with creamy avocado and Swiss cheese. These have so much flavor you won't even miss the meat! Served with some Skinny Fries or Carrot Fries for a perfect meal.

These vegetarian burgers are truly delicious. Between the portobello mushrooms marinated in balsamic vinegar and Worcestershire sauce, the creamy avocado, and the melted Swiss cheese - you seriously won't taste a better veggie burger. Truth be told, I have been making these for years but they seemed to simple to share. However, after lots of requests for portobello burgers, I decided to share this simple recipe. The burgers can be cooked on the grill or under the broiler. Just follow the same directions for cooking under the broiler.

The other thing I love about these burgers is they are one of the best ways to get meat eaters to go for a meatless meal. If you load them up with enough yummy toppings, some people won't even notice. And once they do, they will already be hooked. 

One other trick - these also make a really awesome burger bun. It's a great way to lessen the carbs in a standard burger and make things a little healthier.

How to make portobello burgers?

  • Prep: Make sure to start by cleaning the mushrooms and removing the stem from the mushrooms. Brush the gills with a paper towel to remove any dirt. You can quickly rinse them as well, just make sure to dry them so they don't absorb too much water.
  • Add flavor: Mushrooms are like sponges and take on flavor really well SO you will definitely want to add flavor to your burger through a marinade, spice rub, or dressing. My personal favorite is a quick marinade with balsamic vinegar, olive oil, and some kind of salty and umami element. It could be soy sauce, Worcestershire sauce, coconut aminos, or even something like mustard, which naturally contains a good amount of salt. Then you can spice things up with any dried herbs, spices, or seasonings you like. 
  • On the grill: This is my favorite way to cook portobellos mushroom since the grill adds char and some smoky flavor to the mushrooms. Generally speaking, large mushrooms take about 4-5 minutes per side. Flip the mushroom when there are grill marks and the mushroom releases easily from the grates. 
  • In the oven: These can also be cooked in the oven. I find they come out best when they are broiled. Simply place them on a baking sheet covered with foil and broil for 4-5 minutes per side. 
  • In a skillet: Another option is right on the stovetop. Just add them to a hot skillet, I like to use cast iron, and cook for 4-5 minutes per side. You will need a touch of oil so they don't stick.

Portobello mushroom burger on the grill  wit melted Swiss cheese.

How many calories are in a mushroom burger? 

Portobello mushrooms only have 25-30 calories each so they are a super low calorie option for burgers. They also only have 3-4 grams of carbs. This number will change as soon as you start adding toppings, cheese, buns, etc.

Tips and Recipe Ideas

  • If you are a strict vegetarian, make sure to look for a Worcestershire that is vegetarian or vegan. Some sauces contain anchovy so its something to look out for if you don't eat animal products.
  • Although I love Swiss cheese on this burger, any cheese is fair game. I have made them with cheddar, goat cheese, blue cheese, and pepper jack and it is delicious no matter how you serve it.
  • If the avocado isn't your thing, replace the avocado with another creamy condiment. I love using hummus, tzatziki, salsa, or homemade ranch dressing.

Topping Ideas 

Once you learn how to cook a really awesome portobello mushroom, you can top these meatless burgers with almost anything. We love Swiss cheese and avocado, like we included in the recipe, but here are some other favorites:

  • Mexican style: Top the burger with guacamole, sliced jalapeno, queso fresco, and tomato slices. Amazing.
  • Green goddess: Layer lots of fresh herbs on top or make a quick green goddess dressing with basil, cilantro, parsley, lemon juice, and yogurt or light mayo.
  • Greek: Add roasted red peppers, arugula, red onion, cucumbers, and feta cheese.
  • Barbecue: It's all about the barbecue sauce, pickles, and red onions for this option. And you could always add some vegetarian or turkey bacon.
  • Blue cheese: Blue cheese makes everything better and adding blue cheese, tomatoes, lettuce, and a healthy drizzle of buffalo sauce is pretty darn delicious.

Looking for more vegetarian burger recipes:

Here are some of the tools and products I used to prepare this recipe:

  • If you don't have a gas or charcoal grill at home, a grill pan is a great option for grilling indoors. I used one for years when I lived in an apartment that didn't allow grills. The two that I use most often are this nonstick version and this cast iron version. The nonstick is great for easy clean-up but the cast iron will give you deeper grill marks and more smoky flavor.
The Recipe
Portobello burgers with avocado, swiss cheese, tomatoes, and lettuce on a bun.

Portobello Mushroom Burgers

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  • 4 portabella mushroom caps
  • 2 tbsp balsamic vinegar
  • 1 tbsp olive oil
  • 1 tbsp Worcestershire sauce (vegan if needed)
  • 1.5 tsp Montreal steak seasoning
  • 1 red onion, sliced
  • 4 slices low fat Swiss cheese (like Jarlsberg)
  • 1 tomato, sliced
  • 1 avocado, sliced
  • 2 cups arugula
  • 4 reduced calorie hamburger buns

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Stir together the balsamic vinegar, Worcestershire sauce, olive oil, Italian seasoning, and steak seasoning. Marinate the mushrooms in this mixture for at least 30 minutes.


When ready to grill, remove the mushrooms from marinade letting excess drip off. Grill for 4-5 minutes on each side. Add the cheese right before the mushrooms finish cooking so it melts. At the same time, grill the red onions. Usually I spray mine with cooking spray or brush with olive oil before placing them on the grill.


Top with tomato, arugula, grilled red onion, and avocado.

Nutritional Facts
Serving Size: 1 burger
Amount Per Serving
Calories 299
Calories from Fat 122
% Daily Value *
Total Fat 13g
Saturated Fat 3g
Monounsaturated Fat 1g
Polyunsaturated Fat 0g
Cholesterol 10mg
Sodium 642mg
Total Carbohydrate 36g
Dietary Fiber 9g
Sugars 9g
Protein 15g

* Percent Daily Values are based on a 2,000 calorie diet. Your daily values may be higher or lower depending on your calorie needs.

The Nutritional Values provided are estimates only and may vary based on the preparation method.

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About the author Meet Kristen McCaffrey
Hi, I’m the cookbook author, recipe developer, and food enthusiast behind Slender Kitchen. I am obsessed with making healthy food that is easy to prepare and absolutely delicious. Meal planning is my secret weapon and I hope I can make meal time easier for you with our tried and tested recipes and foolproof meal plans. Learn More
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On Portobello Mushroom Burgers
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Donna J Burchfield
August 21, 2018 - 14:46
Love these recipes. Thanks
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April 10, 2019 - 15:25
Thanks!! So glad to hear you are enjoying them.
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