Equipment
Ingredients
Mushrooms & Marinade
- 4 large portobello mushrooms, stems removed, gills scraped clean if desired
- 45 ml balsamic vinegar
- 45 ml olive oil
- 15 ml soy sauce
- 2 garlic, minced
- 2 g dried thyme
Assembly
- 120 g gruyère cheese, sliced or grated
- 4 burger buns, split
- ½ red onion, thinly sliced rings
- 1 tomato, sliced
- 4 lettuce leaves, washed and dried
- 60 ml mayonnaise
Nutrition (per serving)
Nutrition is estimated per serving. Nutrients without complete source data are omitted.
Full nutrition
- Calories
- 460 kcal
- Protein
- 13 g
- Carbohydrates
- 17 g
- Fat
- 33 g
- Fiber
- 2 g
- Sugar
- 5 g
- Sodium
- 601 mg
- Saturated Fat
- 9 g
- Trans Fat
- 0 g
- Monounsaturated Fat
- 14 g
- Polyunsaturated Fat
- 9 g
- Cholesterol
- 39 mg
- Potassium
- 326 mg
- Calcium
- 373 mg
- Iron
- 1.9 mg
- Magnesium
- 23 mg
- Phosphorus
- 255 mg
- Zinc
- 1.6 mg
- Vitamin A
- 215 mcg
- Vitamin C
- 7 mg
- Vitamin D
- 0.3 mcg
- Vitamin E
- 2.3 mg
- Vitamin K
- 71 mcg
- Vitamin B6
- 0.3 mg
- Vitamin B12
- 0.5 mcg
- Thiamin
- 0.09 mg
- Riboflavin
- 0.17 mg
- Niacin
- 1.6 mg
- Folate
- 55 mcg
- Water
- 90 g
- Alcohol
- 0 g
- Caffeine
- 0 mg
Sources: Aggregated Public Data, USDA FoodData Central
Method
Wipe the mushroom caps clean with a damp paper towel. Whisk together balsamic vinegar, olive oil, soy sauce, minced garlic, and thyme in a small bowl.
Brush the marinade generously over both sides of the mushroom caps. Let them sit at room temperature for 15 minutes to absorb the flavors.
Preheat your grill or grill pan to medium-high heat (approx. 200°C/400°F).
Grill the mushrooms cap-side down first for 4-5 minutes until grill marks appear and they begin to soften.
Flip the mushrooms. Top each cap with the sliced Gruyère cheese. Cover the grill (or pan) with a lid to help the cheese melt, cooking for another 3-4 minutes.
While the cheese melts, place the split buns on the cooler side of the grill to toast until golden brown, about 1-2 minutes.
Spread mayonnaise on the toasted buns. Layer the bottom bun with lettuce, tomato, the cheesy mushroom cap, and red onion. Cap with the top bun and serve immediately.
Chef's Notes
- Scraping the black gills out with a spoon before marinating removes potential bitterness and prevents the burger from dripping dark liquid, though it is not strictly necessary.
- Gruyère has a distinct nuttiness that pairs perfectly with the earthiness of mushrooms. If unavailable, Swiss cheese or sharp white cheddar are decent substitutes.
- For a better crust, place a heavy pan or burger press on top of the mushrooms during the first few minutes of grilling.
- Ensure your grill is properly preheated; a low temperature will cause the mushrooms to steam in their own juices rather than sear.
Storage
Refrigerator: 2 days — Store components separately. Reheat mushrooms gently.
Troubleshooting
Burger is dripping with excess liquid
Cause: Mushrooms released too much water during cooking or were washed with water during prep
Fix: Let the cooked mushrooms rest on a wire rack for 1 minute before assembling to drain excess moisture.
Prevention: Never soak mushrooms; wipe with a damp cloth only. Grill cap-side down first to allow juices to drain.
Cultural Context
The Portobello burger gained immense popularity in the 1990s as the definitive 'veggie burger' option in steakhouses. The Portobello is simply a mature Cremini mushroom, valued for its dense, meat-like texture and large size that mimics a beef patty.
