Portobello Mushroom Burger

My portobello mushroom burger is a scrumptious, meatless alternative to a classic burger, loaded with lots of savory, earthy flavor. Layered with a marinated and grilled portobello mushroom cap, cheese, spicy arugula greens, a tangy sun-dried tomato mayo, plus crispy shallots, this tasty vegetarian burger is healthy comfort food at its most delicious!

The Meatless Alternative to a Classic Burger

While I am definitely a sucker for a big, juicy, classic cheeseburger with all the fixings, I also really love to try out the various meatless alternatives offered on menus these days, if they're packed with lots of savory flavor.

Because I adore veggies, I'll typically opt for a hearty, grilled vegetable-based burger or sandwich, if I'm craving a vegetarian option, one brimming with a tasty sauce and other fresh toppings.

So, I figured it'd be fun to experiment a bit in my own kitchen and create a portobello mushroom burger brimming with the flavors that I love!

I'm talking a marinated portobello mushroom cap that's grilled until tender and juicy, topped with cheese, plus other bells and whistles such as peppery arugula, a savory and bright sun-dried tomato mayo flavored with fresh chives, plus a wild little “nest” of crispy-fried shallots for lots of savory crunch in every bite.

Piled onto a brioche bun, my portobello mushroom burger recipe is the perfect pick for a meatless Monday, or any time I'm looking to enjoy a delicious vegetarian option that's filled to the gills with texture and mouthwatering flavor!

My Portobello Mushroom Burger Recipe

When creating this tasty little mushroom burger, I wanted to be sure there were layers of flavors in each bite, and lots of “meaty” texture to make it filling and satisfying.

Because the portobello mushroom cap is meant to be the star of this burger, I first marinate it in a bit of balsamic vinegar, Dijon mustard, dried herbs, garlic and spices for lots of earthy flavor.

Then, the portobello cap hits the grill pan for a few minutes on each side, just until it becomes tender.

And, since no burger is complete without a zippy savory sauce to spread over both the top and bottom buns, I mix together a simple sun-dried tomato mayo with finely minced sun-dried tomatoes, a bit of lemon, a touch of garlic, and a sprinkle of fresh chives folded in.

To create that bit of crunchy texture to contrast the tender grilled portobello cap, I top things with a little mound of seasoned, crispy shallots for a crisp crunch!

Here's a glance at my portobello mushroom burger recipe: (or just jump to the full recipe...)

1. To get started, I prepare my crispy shallots, then set aside to have ready.
2. Next, I shake up my marinade for my portobello caps, place those caps into a large ziplock bag, and pour the marinade over them to marinate for about 20 minutes before grilling them.
3. While they marinate, I whisk together my sun-dried tomato mayo, and keep that cold in the fridge.
4. Next, I grill my portobello mushroom caps for about 5 minutes on each side, just until tender, and top them with cheese while still hot.
5. Then, to build my portobello mushroom burgers, I generously slather onto both the bottom and top buns some of my sun-dried tomato mayo, add some arugula and sliced tomatoes to the bottom bun, add a grilled portobello cap, top that with some crispy shallots, then cover with the top bun, and enjoy!

Recipe

Portobello Mushroom Burger

by Ingrid Beer

Print Recipe

This portobello mushroom burger is topped with mozzarella, crispy shallots, sun-dried tomato mayo, plus spicy arugula on a brioche bun!

Category: Sandwich
Cuisine: American

Yield: 4 portobello mushroom burgers

Nutrition Info: 605 calories per burger (with 2 tablespoons shallots and 2 tablespoons mayo)

Prep Time: 40 minutes
Cook time: 20 minutes
Total time: 1 hour

Portobello Mushroom Burger Ingredients:

• ¼ cup balsamic vinegar
• 1 teaspoon Dijon mustard
• 1 teaspoon Italian seasoning
• ½ teaspoon salt
• Pinch black pepper
• 2 cloves garlic, pressed through garlic press
• ½ cup olive oil
• 4 portobello mushroom caps, stems cut off and gills scraped out
• 4 slices mozzarella cheese
• 4 brioche buns
• Arugula greens
• Tomato slices

Crispy Shallots Ingredients:

• 2 large shallots, thinly sliced (about 1 heaping cup worth)
• Salt
• Black pepper
• 3 tablespoons flour
• Peanut or vegetable oil, for frying (about 2 to 3 cups)

Sun-Dried Tomato Mayo Ingredients:

• ½ (heaping) cup mayonnaise
• ¼ cup sun-dried tomatoes, minced (if packed in oil, then drain and pat dry)
• 3 cloves garlic, pressed through garlic press
• ¼ teaspoon lemon zest
• 1 ½ teaspoons lemon juice
• 1 (heaping) tablespoon minced chives
• Pinch salt (scant ¼ teaspoon, roughly)
• Pinch black pepper

Preparation:

1. Begin by gathering and prepping all of your crispy shallot ingredients according to the ingredient list above to have ready and organized for use.
2. To make your crispy shallots, add the thinly sliced shallots to a large bowl, sprinkle with salt and pepper, as well as the flour, and toss to coat.
3. Add the oil to a small pot so that it comes about 2 inches up the side (roughly 2 to 3 cups worth), and heat until shimmering (roughly 350° to 360°). Once hot, add about half of the shallots to the oil and allow them to crisp up for a couple of minutes, until golden brown. Remove from pot with a spider or slotted spoon, and place onto a paper towel-lined plate or bowl to drain. Sprinkle with a touch more salt/pepper.
4. Then, gather and prep all of your portobello mushroom burger ingredients according to the ingredient list above to have ready and organized for use.
5. To a small mason-style jar (one with a lid), add the balsamic vinegar, Dijon mustard, Italian seasoning, salt, pepper, garlic and olive oil, and shake vigorously until completely blended.
6. Place the cleaned portobello mushroom caps into a large ziplock bag, and pour the marinade over them, gently massaging the bag to get even coverage of the marinade. Allow the caps to marinate for 20 minutes.
7. While the portobello mushrooms marinate, gather and prep all of your sun-dried tomato mayo ingredients according to the ingredient list above to have ready and organized for use.
8. To prep the mayo, add all of the ingredients to a bowl, and whisk/fold together until completely blended. Set aside in the fridge until ready to use.
9. Once the portobello caps have marinated, place a large grill pan misted with cooking spray over medium-high heat. Once hot, remove the portobello mushroom caps from the marinade (shaking off any excess marinade as much as possible), and place them onto the grill pan (with their stem-side facing up) to grill for about 5 minutes on that first side.
10. Flip the caps and grill them on the second side for another 5 minutes. Once tender, add a slice of cheese to each, and allow it to melt while the caps are still hot (if the cheese needs extra help, place the caps under the broiled for about 30 seconds until the cheese melts).
11. To assemble the portobello mushroom burgers, generously spread both bottom and top buns with the sun-dried tomato mayo, then add some arugula greens and some slices of tomato. Add the grilled portobello mushroom cap over this, then place a little “nest” of the crispy-fried shallots over that, cover with the top bun, and enjoy.

Tips & Tidbits for my Portobello Mushroom Burger recipe:

• Opt for portobello mushroom caps that are bigger than the bun: For these burgers, I'm using a brioche bun which is on the smaller side, so I'm opting for portobello caps that are medium large. If you're using buns that are larger, then try to roughly match the size of the portobello mushroom caps to the general size of the buns so that everything stacks well.
• Swap store-bought crispy onions for the shallots: If you'd prefer to skip the step of crispy-frying the shallots, you can substitute store-bought crispy-fried onions instead. These may be seasonal (typically found during the holidays), but some markets carry them on shelves year-round, near the canned vegetables.
• Choose your favorite melty cheese: I love a mild and creamy mozzarella cheese over top of my portobello mushroom caps, but other good choices are pepper Jack cheese, smoked gouda, or cheddar cheese.

Craving more delectable sandwiches? Check out this Veggie Burger, this Crispy Eggplant Burger, this Korean BBQ Burger, this Grilled Chicken Sandwich with Pesto, this crispy Fish Sandwich, or this Chicken Burger!