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close up shot of Portobello Mushroom Burger with caramelised onions, cheese, hummus, tomato and watercress
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5 from 6 votes

Portobello Mushroom Burgers

These Portobello Mushroom Burgers are absolutely bursting with flavour! With a simple 4 ingredient marinade, these are sure to be some of the best veggie burgers you've ever had!!
Prep Time15 mins
Cook Time20 mins
Marinating Time5 mins
Total Time35 mins
Course: Lunch
Cuisine: Vegetarian
Servings: 4
Calories: 292kcal
Cost: £2 / $2.50


  • Large Zip Lock Bag
  • Frying Pan & Tongs
  • Sharp Knife & Chopping Board
  • Paper Towels (for cleaning mushrooms)



  • 4 Portobello Mushrooms, stalks removed & cleaned with damp paper towel
  • 2 tbsp Soy Sauce
  • 1 tbsp Balsamic Vinegar
  • 1 tbsp Worcestershire Sauce
  • 1 tsp Garlic
  • 1 tbsp Olive Oil
  • Salt & Black Pepper, to taste


  • 4 Burger Buns, toasted
  • 4 slices of Tomato
  • 4 tbsp Hummus
  • 4 slices of Cheese, here I use Swiss
  • 1 large Red Onion
  • 1 tsp Brown Sugar
  • 1 handful Watercress


  • In a zip lock bag, combine your mushrooms with the marinade. Mix it around so all of the mushrooms are coated, then allow to marinate for 30mins - 1 hour, or as long as you have time for. I wouldn't go past 1 hour because they start to shrink from the acidity. Even 5mins makes the world of difference.
  • Place your mushrooms facing down on a pan over medium heat and fry 4-5mins. Flip, then top with cheese and fry for another 5mins or until tender. Timings will depend on the size and shape of your mushrooms.
  • Remove from pan, leaving any leftover juice, then add your onions. Fry until soft, then add sugar and continue frying until caramelised. For the best caramelised onions you want to fry low over a long period of time to release their natural sugars, but for convenience this works just fine!
  • Top your bottom burger bun with hummus, then watercress, then tomato, next with your mushroom burger, topped with your onions and finished with the top bun. Enjoy!



a) Cleaning - Although it seems 'extra' to clean your mushrooms with a damp paper towel, I encourage you to NOT rinse the mushrooms. That'll pack in more moisture than there already is and make for a sloppy mushroom burger.
b) Toasted Buns - Highly recommend toasting the burger buns, this gives a nice crispy texture contrast to the soft mushroom burger.
c) Additional Toppings - Grilled halloumi works great in this burger, as do roasted red pepper and avocado. Can also add crispy bacon if you're a meat eater.
d) Calories - Based on the assumption that all the marinade is used, which is of course an over estimate. Also including the toppings listed in the recipe card. Calories per burger.


Calories: 292kcal | Carbohydrates: 32.79g | Protein: 11.68g | Fat: 13.28g | Saturated Fat: 5.455g | Polyunsaturated Fat: 1.492g | Monounsaturated Fat: 5.52g | Trans Fat: 0.013g | Cholesterol: 19mg | Sodium: 1039mg | Potassium: 622mg | Fiber: 3.4g | Sugar: 11.08g | Vitamin A: 1350IU | Vitamin C: 11.6mg | Calcium: 280mg | Iron: 2.2mg