RecipesCuisine: American-inspired 25 August 2026 Updated at: 25 August 20261 min read

Grilled Portobello Mushroom Burger Recipe

Name: Grilled Portobello Mushroom Burger Recipe
Prep time: 15 min
Cook time: 18 min
Total time: 33 min
Yield: 4
Cuisine: American-inspired
Ingredients: 4 large portobello mushrooms; 3 tbsp soy sauce; 2 tbsp olive oil; 1 garlic clove, finely chopped or crushed; 1 tbsp finely chopped fresh chives; 1 tsp dried oregano; Freshly ground black pepper, to taste; 4 slices provolone or mature Cheddar made with vegetarian rennet; 4 brioche burger buns suitable for vegetarians; 1 tomato, sliced; 1 small red onion, thinly sliced; 1 handful rocket; Your preferred burger sauce, to serve (optional)

Juicy portobello mushrooms marinated with soy, garlic and herbs, grilled until tender and served in brioche buns with cheese, rocket and red onion.

Portobello mushrooms make a satisfying meat-free alternative for a relaxed barbecue. Their firm texture stands up well to the heat, while a simple soy, garlic and herb marinade adds plenty of savoury flavour.

Grill the mushrooms until tender, melt over your preferred cheese and serve them in toasted brioche buns with rocket, tomato and red onion. It is a straightforward vegetarian burger made for summer lunches and easy outdoor gatherings.

Recipe details

Preparation: 15 min
Cooking: 18 min
Serves: 4
Difficulty: Easy

Ingredients

4 large portobello mushrooms
3 tbsp soy sauce
2 tbsp olive oil
1 garlic clove, finely chopped or crushed
1 tbsp finely chopped fresh chives
1 tsp dried oregano
Freshly ground black pepper, to taste
4 slices provolone or mature Cheddar made with vegetarian rennet
4 brioche burger buns suitable for vegetarians
1 tomato, sliced
1 small red onion, thinly sliced
1 handful rocket
Your preferred burger sauce, to serve (optional)

Method

Wipe the mushrooms clean, remove the stems and place the mushroom caps in a shallow dish.
Whisk together the soy sauce, olive oil, garlic, chives, oregano and black pepper.
Pour the marinade over the mushrooms, turn to coat and leave for 15 minutes.
Prepare the barbecue for direct cooking over a medium-high heat. Lightly oil the cooking grate if needed.
Place the mushrooms on the barbecue and cook for 6-8 minutes on each side, brushing with the remaining marinade as they cook, until tender and piping hot.
Add the cheese during the final 2 minutes and close the lid briefly to help it melt. Toast the cut sides of the buns at the same time, watching carefully so they do not burn.
Fill each bun with rocket, tomato, a grilled mushroom, red onion and your preferred sauce.
Serve immediately.