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Portobello burger with lettuce, tomato, pickle on a white plate.

Portobello Burgers

  • Author: Alison Andrews
  • Prep Time: 15 mins
  • Cook Time: 20 mins
  • Total Time: 35 minutes
  • Yield: 4
  • Diet: Vegan


These portobello burgers are marinated and then grilled to absolute perfection. Serve fully loaded in soft rolls with caramelized onions, lettuce, tomato, pickles and avocado. So easy and so delicious. 


Portobello Burgers:

  • 4 Portobello Mushrooms (Stems Removed)
  • 1/2 Tbsp Grapeseed Oil*


Caramelized Onions:

  • 1/2 Tbsp Olive Oil
  • 1 Medium Onion (White, Yellow or Brown, Chopped)
  • 1 Tbsp Soy Sauce
  • 2 Tbsp Maple Syrup


  • Hamburger Rolls
  • Lettuce
  • Tomato
  • Dill Pickles
  • Avocado


  1. Remove the stems from the portobello mushrooms. 
  2. Prepare your marinade by adding soy sauce, paprika, maple syrup, brown sugar, tomato paste, liquid smoke and oregano to a measuring jug. Whisk together until well mixed. 
  3. Place the mushrooms on a baking tray or in a shallow dish and brush generously with the marinade on both sides. Leave them to soak in the marinade for 15 minutes.
  4. While the mushrooms are marinating, make your caramelized onions. Add chopped onions and olive oil to a frying pan and sauté until the onions are softened. 
  5. Add soy sauce and maple syrup and sauté with the onions until sticky and caramelized.
  6. Heat up a grill pan and then brush it with 1/2 tablespoon of high smoke oil (we used grapeseed oil). 
  7. Add the mushrooms and fry for around 3 minutes each side at medium heat. 
  8. Then turn off the heat and brush both sides with marinade. 
  9. Serve the portobello burgers on hamburger rolls with lettuce, sliced tomato and sliced dill pickles and topped with the caramelized onions and sliced avocado. 


*Grapeseed oil – you can use any high heat oil that has a high smoke point. We used grapeseed oil and that worked very well. 

*Grill pan – you can use a grill pan like we did for your portobello mushrooms but if you don’t have a grill pan then a regular frying pan or skillet will work just fine. You won’t get the grill lines but everything else will be the same. 

*Leftovers: Keep leftover portobello burgers in a covered container in the fridge and enjoy within 2-3 days. They are not freezer friendly. 

*Nutritional information is for 1 burger (of 4) and includes everything (roll, garnishes, onions, avocado)

  • Category: Entree, Savory
  • Method: Stovetop
  • Cuisine: Vegan


  • Serving Size: 1 Burger (of 4)
  • Calories: 383
  • Sugar: 25.7g
  • Sodium: 1359mg
  • Fat: 11.9g
  • Saturated Fat: 2g
  • Carbohydrates: 62.8g
  • Fiber: 8.1g
  • Protein: 11.4g

Keywords: portobello burgers, portobello mushroom burgers