Grilled Portobello Burgers with Piquillo Aioli
Recipe type: Main Dish, Sandwich
Serves: 6 burgers
For the aioli:
  • ½ cup chopped drained piquillo peppers from a jar, (or roasted red peppers in a pinch)
  • 1 tablespoon red wine vinegar
  • 2 teaspoons finely chopped fresh thyme leaves
  • 1 garlic clove, minced
  • ½ cup mayonnaise or veganaise
  • ground cayenne to taste
  • salt to taste
If making the aioli from scratch (ie: homemade mayonnaise), you will need the following...
  • 1 egg yolk, preferably organic
  • ¼ cup olive oil
  • ¼ cup grapeseed or olive oil
  • ⅛ tsp salt, or to taste
For the portobello burgers:
  • 6 large portobello mushrooms; washed, stems removed, gills scraped out with a spoon
  • 1 sweet onion, cut into ⅓ inch slices
  • 2 teaspoons chopped fresh thyme leaves
  • 2 garlic cloves, minced
  • 6 slices smoked gouda
  • 6 sourdough or ciabatta rolls
  • 1 bunch watercress, stems trimmed, or a handful of mixed greens
  1. For the aioli (from scratch): Whisk the egg yolks and salt together in a small bowl, then pour into a food processor. Add the minced garlic, piquillo peppers, thyme and vinegar. Blend for about 30 seconds until pureed. With the food processor continuously running, pour in the oil followed by the olive oil in a slow and steady stream. Remove from the food processor and season to taste with salt, cayenne, and black pepper. Chill until ready to serve. This aioli can be made up to 3 days in advance if refrigerated immediately.
  2. For the aioli (if using prepared mayonnaise): Combine the piquillo peppers, garlic, thyme, and red wine vinegar in a food processor and blend until pureed. Add the mayonnaise and pulse for about 3 seconds to combine. Remove the mixture to a small bowl and season to taste with salt, black pepper, and cayenne. Chill until ready to serve.
  3. Arrange the portobellos on a baking sheet. Brush both sides with oil. Rub each side with minced garlic, thyme, salt and pepper. Allow mushrooms to sit, gill side up for at least 30 minutes and up to 2 hours. Lightly brush the onions with oil and sprinkle with salt.
  4. Lightly oil the grates of a grill or grill pan and pre-heat over medium-high heat. Place the onions and mushrooms on the rack, and cook until grill marks appear, about 4 minutes. Flip and cook another 6-8 minutes, or until mushrooms are tender and striped with grill marks. Place 1 slice of gouda on top of each mushroom, and cook until gouda is melted, about 1 minute. Slice each sourdough roll in half and place on the grill until toasted.
  5. Spread aioli on the cut side of each roll. Top each roll with a mushroom, grilled onions and watercress. Serve immediately while hot.
Recipe by Spoon With Me at