The Best Grilled Portobello Mushroom Burger is a culinary delight that promises to satisfy both vegetarians and meat lovers alike. This flavorful burger features marinated, grilled portobello mushrooms topped with melted Swiss cheese, fresh vegetables, and creamy avocado. Perfect for summer barbecues or a quick weeknight dinner, this recipe elevates the classic burger experience with its earthy flavors and hearty texture.
Why You’ll Love This Recipe
- Delicious Flavor: The marinade infuses the mushrooms with rich flavors that are hard to resist.
- Healthy Option: Lower in calories compared to traditional beef burgers, this dish is packed with nutrients.
- Quick Preparation: With just 30 minutes of prep time, you can whip up a fantastic meal in no time.
- Customizable Toppings: Feel free to add your favorite toppings for a personalized touch.
- Grill-Friendly: Ideal for outdoor cooking, making it great for gatherings and BBQs.
Tools and Preparation
Before diving into this delicious recipe, gather your tools and equipment. Having everything ready will streamline the cooking process and ensure a delightful grilling experience.
Essential Tools and Equipment
- Grill or indoor grill pan
- Large bowl
- Whisk
- Basting brush
- Tongs
Importance of Each Tool
- Grill or indoor grill pan: Provides the perfect cooking surface for achieving those lovely grill marks and smoky flavor.
- Large bowl: Essential for mixing and marinating the sauce thoroughly.
- Whisk: Helps in combining the marinade ingredients evenly for maximum flavor.
- Basting brush: Ensures even distribution of marinade on the mushrooms while grilling.
Ingredients
I set out to make a great tasting grilled portobello mushroom burger that even a meat lover would love. The mushrooms are marinated then grilled and topped with melted Swiss Cheese, grilled red onion, tomatoes, spinach, and avocado – yum!!
For the Burger
- 4 portobello mushroom caps
- 2 tbsp balsamic vinegar
- 1 tbsp low sodium soy sauce
- 1 tablespoon olive oil
- 1 tbsp chopped rosemary
- 1-1/2 tsp steak seasoning like Montreal Steak Grill Mates
- 4 thick slices red onion
- 4 oz reduced fat Swiss (sliced thin)
- 4 thin slices tomato
- 1/2 avocado (sliced thin)
- baby spinach
- 4 whole wheat low calorie buns (I used Martin)
For Garnish
- 2 tablespoons fresh parsley, finely chopped

How to Make The Best Grilled Portobello Mushroom Burger
Step 1: Prepare the Marinade
In a large bowl, whisk together balsamic vinegar, soy sauce, olive oil, rosemary, and Montreal steak seasoning until well combined.
Step 2: Marinate the Mushrooms
Place the portobello mushroom caps in the bowl with the marinade. Toss them gently using a spoon to ensure they are evenly coated. Let them stand at room temperature for 20 to 30 minutes, turning occasionally.
Step 3: Preheat the Grill
Heat your grill or indoor grill pan over medium heat. Once hot, brush the grate with oil or lightly spray the grill pan to prevent sticking.
Step 4: Grill the Mushrooms
Carefully place the marinated mushrooms on the grill. Reserve some marinade for basting later. Grill each side for about 5 to 7 minutes or until tender, basting frequently with marinade.
Step 5: Add Cheese
During the last minute of cooking, place slices of Swiss cheese on top of each mushroom cap to melt perfectly.
Step 6: Grill Onions and Buns
While grilling mushrooms, add thick slices of red onion to the grill. Cook for about one minute on each side until slightly charred. Also grill your whole wheat buns until toasted.
Step 7: Assemble Your Burger
To finish off your burger creation, start by placing baby spinach on each bun followed by a grilled portobello mushroom cap. Top with grilled onions, sliced tomatoes, and avocado before closing with the top bun. Enjoy your delicious grilled portobello mushroom burger!
How to Serve The Best Grilled Portobello Mushroom Burger
Serving the best grilled portobello mushroom burger can enhance your dining experience. Here are some great suggestions to take this dish to the next level.
Classic Pairings
- Fries: Crispy French fries or sweet potato fries make a great side.
- Salad: A light green salad with vinaigrette adds freshness.
- Pickles: Tangy pickles provide a crunchy contrast.
Gourmet Touches
- Balsamic Glaze: Drizzle balsamic reduction over the burger for extra flavor.
- Sautéed Mushrooms: Add extra sautéed mushrooms on top for a double dose of umami.
Unique Twists
- Pico de Gallo: Fresh salsa can add zest and brightness.
- Guacamole: Creamy guacamole pairs well with the mushroom’s texture.
How to Perfect The Best Grilled Portobello Mushroom Burger
To truly master the best grilled portobello mushroom burger, consider these helpful tips.
- Bold Marinade: Use a robust marinade to infuse flavor into the mushrooms.
- Grill at Medium Heat: This helps achieve perfect tenderness without burning.
- Cheese Melting Time: Add cheese during the last minute of grilling for optimal meltiness.
- Fresh Ingredients: Always use fresh veggies for toppings to enhance taste and nutrition.
- Proper Basting: Baste mushrooms frequently while grilling for added moisture and flavor.

Best Side Dishes for The Best Grilled Portobello Mushroom Burger
Complementing your grilled portobello mushroom burger with sides can elevate your meal. Here are some delicious options to consider.
- Coleslaw: A crunchy, tangy coleslaw adds a refreshing crunch.
- Corn on the Cob: Sweet corn is an excellent summer side that pairs nicely.
- Quinoa Salad: A protein-packed quinoa salad offers a nutritious option.
- Potato Wedges: Seasoned potato wedges provide extra heartiness to your meal.
- Roasted Vegetables: Colorful roasted veggies add both flavor and nutrition.
- Chips and Salsa: A simple yet satisfying crunchy side that complements any burger.
Common Mistakes to Avoid
Making The Best Grilled Portobello Mushroom Burger can be a delightful experience, but common mistakes can hinder your results.
- Over-marinating the mushrooms: Letting the mushrooms soak too long can make them too salty and mushy. Stick to the recommended 20 to 30 minutes for optimal flavor and texture.
- Neglecting to preheat the grill: If the grill is not hot enough, the mushrooms may become soggy instead of achieving that perfect char. Always preheat your grill for at least 10 minutes before cooking.
- Using low-quality cheese: Using inferior cheese can result in a lackluster flavor. Opt for high-quality Swiss cheese for a rich taste that complements the mushrooms beautifully.
- Skipping the basting step: Basting the mushrooms with marinade while grilling adds moisture and enhances flavor. Don’t forget to brush them regularly for the best results.
- Not using fresh ingredients: Fresh ingredients greatly enhance the overall taste of your burger. Always choose ripe tomatoes, fresh spinach, and firm avocados for maximum flavor.
Storage & Reheating Instructions
Refrigerator Storage
- Store leftovers in an airtight container.
- The Best Grilled Portobello Mushroom Burger will last up to 3 days in the fridge.
- Keep all components separate if possible to maintain freshness.
Freezing The Best Grilled Portobello Mushroom Burger
- Freeze individual components separately for best texture.
- Cooked portobello mushrooms can be frozen for up to 2 months.
- Use freezer-safe containers or bags to prevent freezer burn.
Reheating The Best Grilled Portobello Mushroom Burger
- Oven: Preheat your oven to 350°F (175°C) and reheat for about 10-15 minutes until warmed through.
- Microwave: Place burger on a microwave-safe plate and heat on medium power in 30-second intervals until hot.
- Stovetop: Heat a skillet over medium heat and warm each component for about 3-5 minutes, flipping as needed to prevent burning.

Frequently Asked Questions
What makes The Best Grilled Portobello Mushroom Burger so special?
The combination of marinated portobello mushrooms grilled to perfection, topped with melted Swiss cheese and fresh veggies creates an incredible flavor profile that appeals even to meat lovers.
Can I customize my Grilled Portobello Mushroom Burger?
Absolutely! You can add different toppings like spicy aioli, grilled peppers, or even bacon for extra flavor.
How do I know when my portobello mushroom is done grilling?
When the portobello mushroom is tender and has nice grill marks, it’s ready! Usually, this takes about 5-7 minutes per side.
Can I use other types of cheese with this burger?
Yes! While Swiss is delicious, feel free to experiment with mozzarella, cheddar, or provolone based on your preference.
Final Thoughts
The Best Grilled Portobello Mushroom Burger is not only satisfying but also versatile. With its rich flavors and customizable toppings, it’s a perfect choice for any meal. Try this recipe today, and feel free to get creative with your preferred ingredients!

The Best Grilled Portobello Mushroom Burger
The Best Grilled Portobello Mushroom Burger is a delightful culinary creation that brings together the earthy flavors of marinated, grilled portobello mushrooms and the creamy richness of melted Swiss cheese. This burger is a hit among both vegetarians and meat lovers, offering a satisfying, hearty texture that’s perfect for summer barbecues or quick weeknight dinners. Topped with fresh vegetables like tomatoes, spinach, and creamy avocado, this recipe elevates the classic burger experience while keeping it healthy and delicious.
- Total Time: 40 minutes
- Yield: Serves 4
Ingredients
- 4 portobello mushroom caps
- 2 tbsp balsamic vinegar
- 1 tbsp low sodium soy sauce
- 1 tbsp olive oil
- 1 tbsp chopped rosemary
- 1.5 tsp steak seasoning (e.g., Montreal Steak Grill Mates)
- 4 oz reduced fat Swiss cheese (sliced thin)
- 4 thick slices red onion
- 4 thin slices tomato
- 1/2 avocado (sliced thin)
- baby spinach
- 4 whole wheat low-calorie buns
Instructions
- In a large bowl, whisk balsamic vinegar, soy sauce, olive oil, rosemary, and steak seasoning.
- Add portobello caps to the marinade and toss gently to coat. Let sit for 20-30 minutes.
- Preheat your grill or indoor grill pan over medium heat and brush with oil.
- Grill marinated mushrooms for 5-7 minutes per side while basting with reserved marinade.
- During the last minute of grilling, place Swiss cheese on top of each mushroom cap to melt.
- Grill sliced red onion for about one minute per side until charred; toast buns at the same time.
- Assemble by layering spinach on each bun followed by the mushroom cap, onions, tomatoes, and avocado.
- Prep Time: 30 minutes
- Cook Time: 10 minutes
- Category: Main
- Method: Grilling
- Cuisine: American
Nutrition
- Serving Size: 1 serving
- Calories: 320
- Sugar: 3g
- Sodium: 720mg
- Fat: 12g
- Saturated Fat: 4g
- Unsaturated Fat: 7g
- Trans Fat: 0g
- Carbohydrates: 38g
- Fiber: 8g
- Protein: 15g
- Cholesterol: 15mg
Keywords: Feel free to customize your toppings with options like spicy aioli or sautéed mushrooms. Always preheat your grill to ensure the mushrooms achieve a nice char.