Description

These smoky mushroom burgers feature large flat mushrooms filled with a savory mixture of chopped mushroom stalks, roasted red peppers, thyme, breadcrumbs, sundried tomato paste, and smoked paprika. They’re cooked on the barbecue and served on crusty rolls with roasted garlic mayonnaise, caramelized red onions, fresh salad leaves, and a sprinkle of cheddar or Manchego cheese for a delicious vegetarian burger option.

Ingredients

Scale

Mushroom Burgers

4 large flat mushrooms
1 tbsp olive oil, plus extra for frying
2 roasted red peppers (from a jar), finely chopped
½ small pack thyme, leaves picked and chopped
50g fresh breadcrumbs
1 tbsp sundried tomato paste
2 tsp smoked paprika

Caramelized Onions

3 red onions, thinly sliced
1 tbsp golden caster sugar
1 tbsp sherry vinegar

Roasted Garlic Mayo

3 garlic cloves, unpeeled
50g good-quality mayonnaise

To Assemble

4 crusty bread rolls (ciabatta recommended)
salad leaves
25g cheddar or Manchego cheese, grated

Instructions

Prepare the Roasted Garlic Mayo: Wrap the unpeeled garlic cloves in foil and place them on a hot spot of the barbecue or in a hot oven for 20-30 minutes until very soft. Once cooled, squeeze the garlic out of the skins and mash with a fork. Mix the mashed garlic with mayonnaise and chill until ready to serve.
Make the Mushroom Filling: Remove the stalks from the mushrooms and finely chop them. Heat a drizzle of olive oil in a pan over the hob or barbecue, fry the chopped stalks until golden and soft. Add roasted red peppers, thyme leaves, breadcrumbs, sundried tomato paste, smoked paprika, and season with salt and pepper. Cook the mixture for 5 more minutes, then set aside to cool slightly.
Prepare the Mushroom Caps: Rub the mushroom caps with olive oil and season with salt and pepper. Spoon the filling mixture evenly on top of each mushroom cap. The stuffed mushrooms can be chilled for up to one day before cooking.
Caramelize the Onions: Heat a little oil in another frying pan over the hob or barbecue. Add the thinly sliced red onions and cook for 15 minutes until soft and golden. Stir in caster sugar, sherry vinegar, and season with salt and pepper. Continue cooking for 5 more minutes until the onions are caramelized and sticky. These can be chilled for up to two days.
Cook the Mushrooms on the Barbecue: Place the stuffed mushrooms on the barbecue with the filling side up. Close the lid or cover with foil and cook for 20 minutes, ensuring the mushrooms become soft and cooked through. Adjust the heat as needed and move mushrooms to the upper shelf if the bottoms start to burn.
Toast the Bread Rolls: Split the crusty rolls and toast them on the barbecue until warm and slightly crisp.
Assemble the Burgers: Spread garlic mayo on the inside of each roll, add a handful of fresh salad leaves, place a stuffed mushroom on top, layer with sticky caramelized onions, and finish with a generous grating of cheddar or Manchego cheese. Serve immediately.

Notes

You can roast the garlic in a hot oven if you don’t have access to a barbecue.
To prevent mushrooms from burning on the barbecue, keep an eye on the heat and move them to a cooler spot if needed.
The mushroom filling and caramelized onions can be prepared ahead to save time on the day of grilling.
Use ciabatta or other crusty bread rolls that can hold up well to the juicy mushrooms and toppings.
For a vegan option, substitute mayonnaise and cheese with vegan alternatives.

Prep Time: 25 minutes
Cook Time: 40 minutes
Category: Main Course
Method: Grilling
Cuisine: British

Keywords: smoky mushroom burgers, vegetarian burgers, barbecue mushroom recipe, roasted garlic mayo, caramelized onions, grilled mushrooms, easy veggie burger