Ingredients:

  • 4 large portobello mushroom caps, stems removed (approx. 800g / 1.75 lbs)
  • 1/4 cup olive oil (60 ml)
  • 4 cloves garlic, minced (about 12g)
  • 2 tablespoons balsamic vinegar (30 ml)
  • 1 tablespoon fresh rosemary, chopped (4g)
  • 1 tablespoon fresh thyme, chopped (4g)
  • 1 teaspoon dried oregano (2g)
  • 1/2 teaspoon salt (3g)
  • 1/4 teaspoon black pepper (1g)
  • 1/2 cup balsamic vinegar (120 ml)
  • 1 tablespoon brown sugar (12g)
  • 4 burger buns (brioche buns recommended)
  • 4 slices provolone cheese (or your preferred cheese) (approx. 80g / 2.8 oz)
  • Optional toppings: lettuce, tomato slices, red onion slices, pesto, aioli

Instructions:

  1. Prepare the Marinade: Whisk together olive oil, minced garlic, balsamic vinegar, rosemary, thyme, oregano, salt, and pepper in a bowl.
  2. Marinate the Mushrooms: Place portobello caps in the bowl (or zip-top bag) and coat thoroughly with the marinade. Marinate for at least 30 minutes (or up to several hours) in the refrigerator, flipping occasionally.
  3. Make the Balsamic Glaze: In a small saucepan, combine balsamic vinegar and brown sugar. Bring to a simmer over medium heat and cook until reduced by half and thickened to a syrupy consistency (about 5-7 minutes). Watch carefully to prevent burning!
  4. Grill the Mushrooms: Preheat grill to medium heat. Remove mushrooms from marinade (reserve marinade). Grill for 5-7 minutes per side, brushing with reserved marinade during the last few minutes of cooking. Cook until tender and slightly charred.
  5. Add Cheese: During the last minute of grilling, place a slice of cheese on each portobello cap and allow it to melt.
  6. Assemble Burgers: Lightly toast burger buns. Spread with your favorite toppings (pesto, aioli, etc.). Place cheesed portobello cap on the bottom bun, drizzle with balsamic glaze, add additional toppings (lettuce, tomato, red onion), and top with the other half of the bun.
  7. Serve: Serve immediately with your favorite sides.