Marinated Portobello Mushroom Burgers

Just in time for summer! The balsamic marinade gives the mushrooms a wonderful flavor.

My teenage son, who claims to dislike mushrooms, really enjoyed these burgers. He helped me prepare them earlier in the day to allow them to marinate for a few hours; then we grilled them that evening after making some caramelized onions.

I’m hoping to inspire my dad to retry making portobello mushroom burgers. His first attempt didn’t go very well—the mushrooms fell apart when he tried to prepare them. Here’s a delicious recipe with helpful hints!

Marinated Portobello Mushroom Burgers

  • Servings: 4
  • Difficulty: easy
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I used store-bought vegan kale-basil-cashew pesto to spread on whole wheat brioche buns topped with marinated tomatoes, caramelized onions (tip below), and baby spinach.

Credits: Recipe by Oh She Glows — This recipe was taken from “The Oh She Glows Cookbook” by Angela Liddon


Portobello Caps:

  • 4 medium portobello mushrooms
  • 4 tablespoons (60 mL) balsamic vinegar
  • 5 tablespoons (75 mL) fresh lemon juice
  • 4 tablespoons (60 mL) extra-virgin olive oil
  • 2 garlic cloves, minced
  • 2 teaspoons (10 mL) dried oregano
  • 2 teaspoons (10 mL) dried basil
  • 1/2 teaspoon (2.5 mL) finely ground sea salt
  • 1/2 teaspoon (2.5 mL) finely ground pepper


  • pesto (I used vegan kale-basil-cashew pesto; Oh She Glows used a sun-dried tomato kale-hemp pesto)
  • olive oil marinated or sliced heirloom tomatoes
  • caramelized onions (see tip below)
  • baby spinach, kale or lettuce leaves
  • avocado slices


  1. Prepare mushroom caps: Remove the stems from the mushrooms by carefully twisting the stem. With a small spoon, scrape out black gills, careful not to dig into mushroom or they may break. Rub the cap with a damp cloth to clean.
  2. In a dish, sized to fit caps in a single layer, whisk together the vinegar, lemon juice, oil, garlic, oregano, basil, salt, and pepper. Add the portobello caps and toss to coat them in the marinade. Marinate the mushrooms for 30-60 minutes (or all day/overnight), intermittently spooning marinade over them to coat.
  3. Preheat a grill pan or an outdoor grill over medium-high heat. Grill the portobello caps for 4-5 minutes per side, until lightly charred and tender.
  4. Assembly buns with toppings, as desired. Top with portobello caps. Or slice mushrooms and place with toppings into lettuce wraps for a grain-free option.

Tip: To make caramelized onions, thinly slice 2-3 sweet or yellow onions and sauté it over medium heat in 2 tablespoons (30 mL) olive oil until golden and lightly browned, but not burned. It usually take about 30 minutes to bring out the onion’s natural sugars.

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