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Grilled Portobello Mushroom Burger with lettuce, tomato, onion, and mushrooms on a toasted bun.
Maryam

Grilled Portobello Mushroom Burger

Meaty, marinated portobellos grilled until smoky and juicy, piled high with garlic aioli and crisp fixings for the ultimate vegetarian burger that satisfies every craving.
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Prep Time 15 minutes
Cook Time 12 minutes
Total Time 45 minutes
Servings: 4 servings
Course: Main Course
Cuisine: American
Calories: 380
Ingredients Equipment Method Notes

Ingredients
  

For the Mushrooms
  • 4 large portobello mushroom caps wiped clean, stems removed
  • 3 tbsp balsamic vinegar
  • 2 tbsp soy sauce
  • 2 tbsp olive oil plus more for grilling
  • 2 cloves garlic minced
  • 0.5 tsp black pepper freshly ground
For the Garlic Aioli
  • 0.5 cup mayonnaise
  • 1 clove garlic finely grated
  • 1 tsp lemon juice freshly squeezed
For Serving
  • 4 brioche buns toasted
  • 4 slices provolone or swiss cheese optional
  • 2 cups arugula or mixed greens
  • 1 large tomato sliced
  • 0.5 small red onion thinly sliced

Equipment

  • Grill or Grill Pan
  • Basting Brush
  • Small Bowl (for sauce)

Method
 

Marinate the Mushrooms
  1. In a shallow dish, whisk together balsamic vinegar, soy sauce, olive oil, minced garlic, and black pepper. Add the portobello caps and turn to coat both sides. Let marinate at room temperature for 20 minutes, turning once halfway through. The mushrooms will absorb the liquid and darken slightly.
Make the Garlic Aioli
  1. While mushrooms marinate, combine mayonnaise, grated garlic, and lemon juice in a small bowl. Stir well and set aside. The garlic will mellow and infuse the mayo as it sits.
Grill the Mushrooms
  1. Heat your grill or grill pan to medium-high (about 400°F). Brush the grates with oil to prevent sticking.
  2. Remove mushrooms from marinade, letting excess drip off. Grill gill-side down first for 4-5 minutes until grill marks appear. Flip and grill another 4-5 minutes until the mushrooms are tender when pierced with a knife and have released their liquid. If using cheese, add slices in the last minute and close the lid to melt.
Assemble the Burgers
  1. Spread garlic aioli on both halves of the toasted buns. Layer arugula, grilled mushroom, tomato slices, and red onion. Add the top bun and serve immediately while warm.

Notes

Scrape the gills out with a spoon if you prefer a less earthy flavor and neater eating. These mushrooms can be marinated up to 4 hours ahead and held in the refrigerator - just bring to room temperature before grilling. For extra umami, add a splash of Worcestershire sauce to the marinade.