Portobello Mushroom Burger with Mozzarella, Roasted Peppers and Pesto Mayo Recipe

If you’ve ever dreamed of the ultimate vegetarian burger, this Portobello Mushroom Burger with Mozzarella, Roasted Peppers and Pesto Mayo is about to make your taste buds sing! Juicy marinated mushrooms, creamy mozzarella, vibrant roasted peppers, and zesty pesto mayo all tucked into a toasted bun—every bite tastes like summer on a plate, and it’s ready in a flash!

Ingredients You’ll Need

Just a handful of super-fresh, vibrant ingredients bring big flavor to this Portobello Mushroom Burger with Mozzarella, Roasted Peppers and Pesto Mayo. Each element adds its own color, taste, or texture, and using the best you can find makes every component sing.

• Portobello mushroom caps: These are the heart of your burger—meaty, juicy, and absolutely perfect for grilling.
• Balsamic vinegar: Gives the mushrooms a tangy, slightly sweet marinade that deepens the flavor.
• Low sodium soy sauce: Adds an umami kick and extra savory depth.
• Olive oil: Helps keep the mushrooms tender and infuses everything with richness.
• Montreal Steak Seasoning: Brings the magic of backyard burgers, even without meat. You can use any favorite grill seasoning blend.
• Fresh mozzarella: Opt for the best-quality, thinly sliced mozzarella for melting creamy goodness.
• Roasted red pepper: Sweet, vibrant, and luscious, these add color and contrast. Jarred works beautifully in a pinch.
• Red onion: Thick slices add subtle sweetness and a little snap when grilled.
• Whole wheat buns: Soft, hearty buns hold up to all the fillings and bring a nutty flavor. Multigrain works too!
• Pesto: A punchy, herby spread that cuts through the richness—use homemade or your favorite store-bought brand.
• Light mayo: Blends with pesto for a creamy, tangy burger sauce you’ll want on everything.

Variations

Don’t be afraid to play around with this Portobello Mushroom Burger with Mozzarella, Roasted Peppers and Pesto Mayo—personal touches let your burger reflect your cravings and needs. Here are some fun ways to customize your creation!

• Gluten-free buns: Simply swap in your favorite gluten-free buns to keep things wheat-free but every bit as satisfying.
• Dairy-free/Vegan cheese: Sub the mozzarella for your go-to dairy-free slices or leave off the cheese entirely.
• Homemade pesto: Whip up a quick vegan or nut-free pesto to suit allergies or tastes.
• Different veggies: Add avocado, swap the red onion for grilled shallots, or toss on arugula for a peppery bite.
• Spicy kick: Add sliced pickled jalapeños or a smear of Calabrian chili paste to amp up the heat and depth.

How to Make Portobello Mushroom Burger with Mozzarella, Roasted Peppers and Pesto Mayo

Step 1: Make the Pesto Mayo

In a small bowl, simply mix together your pesto and light mayo until well-blended. This creamy, herby spread is the secret sauce that ties the whole burger together and can be made in advance if you’re prepping ahead. Set aside in the fridge until you’re ready to assemble burgers.

Step 2: Marinate the Mushrooms

In a large bowl, whisk together the balsamic vinegar, soy sauce, olive oil, and Montreal Steak Seasoning. Add the portobello mushroom caps and toss gently, spooning the marinade over every surface. Let them sit and soak up those flavors for 20–30 minutes right at room temp, flipping them a couple of times so they’re evenly coated.

Step 3: Fire Up the Grill

Preheat your grill or indoor grill pan over medium heat. Give the grates a little brush of oil or spray just before cooking to keep sticking at bay. Place the marinated mushrooms on, saving that extra marinade for brushing as they cook. Grill each side for about 5–7 minutes, basting every so often, until the mushrooms are juicy and fork-tender.

Step 4: Add the Mozzarella

In the last minute of grilling your mushrooms, lay the slices of fresh mozzarella on top. Close the grill lid or cover the pan just long enough to melt the cheese into irresistible puddles—it should be soft and a little gooey, not rubbery.

Step 5: Grill the Onions and Toast the Buns

While the mushrooms finish, grill the thick onion slices until they have nice char marks—about 1 minute per side is all it takes for smoky flavor and sweet caramelization. Pop the buns onto the grill for a quick toast so their edges get golden and crisp.

Step 6: Assemble the Burgers

Smear that luscious pesto mayo on the bottom (and top, if you like!) of each toasted bun. Layer on the grilled portobello mushroom with melted mozzarella, followed by the grilled onion and sweet roasted peppers. Cap with the other half of the bun and serve immediately. Welcome to burger bliss!

How to Serve Portobello Mushroom Burger with Mozzarella, Roasted Peppers and Pesto Mayo

Garnishes

A handful of peppery arugula or fresh baby spinach adds a pop of green and crunch. Try sprinkling with fresh basil leaves for an extra herby touch, or add a few thin slices of sun-dried tomatoes for a hint of tang.

Side Dishes

This burger practically begs for crispy sweet potato fries, classic potato wedges, or a heap of crunchy slaw. If you want something lighter, a simple lemony green salad or roasted corn on the cob makes for the most refreshing accompaniment.

Creative Ways to Present

Stack your Portobello Mushroom Burger with Mozzarella, Roasted Peppers and Pesto Mayo high and secure it with a colorful bamboo skewer—guaranteed to impress at parties. Or serve deconstructed on a platter so everyone can build their own dream burger, perfect for cookouts and family dinners.

Make Ahead and Storage

Storing Leftovers

Store any leftover grilled portobello caps and toppings in airtight containers in the refrigerator. Keep the pesto mayo and buns separate and assemble just before serving to prevent sogginess. Properly stored, everything will stay fresh for up to 3 days.

Freezing

While pesto mayo and fresh mozzarella don’t freeze well, you can freeze extra grilled portobello mushrooms for up to a month. Cool completely, wrap each cap tightly in plastic, place in a freezer bag, and thaw in the fridge before reheating.

Reheating

To reheat, warm the mushrooms gently in a skillet with a splash of water or in the microwave until heated through. Refresh the buns by toasting, and reassemble with fresh toppings and pesto mayo just before eating.

FAQs

Final Thoughts

This Portobello Mushroom Burger with Mozzarella, Roasted Peppers and Pesto Mayo proves that meatless meals can be outrageously flavorful, quick, and totally festive. I can’t wait for you to fire up your grill and watch everyone fall in love—trust me, this is a burger you’ll want on repeat all summer long. Bon appétit!

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