Grilled Portobello Mushroom Burgers

These burgers are popping with flavor and grill nicely on the grill or a grill pan.


  • 2 large, meaty Portobello mushrooms (4-5” in diameter)
  • 1 slender cucumber, peeled, sliced in half, and then sliced lengthwise into very thin slices
  • 2 medium carrots, cut into 4 ½” matchsticks
  • 10 leaves of Romaine lettuce, sliced into 1” slices
  • 1 onion, sliced into quarters, and then sliced thin for caramelizing
  • 1 medium red bell pepper, sliced in half, seeds removed, and roasted (or 2 bottled peppers)
  • 2 burger buns
  • 4 Tbsp vegenaise mixed with a couple of squirts sriracha, to taste
  • 1/2 Tbsp miso (white or red)
  • 1/2 Tbsp rice wine vinegar
  • 1/2 Tbsp toasted sesame oil, pinch of salt and pepper
  • 1 medium avocado, smashed with a fork in a small bowl
  • salt and pepper to taste
  • 1 medium clove of minced garlic, or 1/4 tsp granulated garlic, to taste


  1. Saute the onions in a small cast iron skillet with a little oil on medium-low heat for about 20 minutes, stirring occasionally, until lightly caramelized and golden brown (if onions get dry in the skillet, add a little water, instead of more oil).
  2. Wipe the mushrooms clean with a damp cloth; remove tough stems and gills. Place 2 Portobello mushrooms, stems side up, in a shallow container that is large enough to marinate the 2 mushrooms.
  3. Whisk the marinade ingredients (miso, rice wine vinegar, toasted sesame oil, pinch of salt and pepper) together and brush liberally onto both sides of the mushrooms and set aside to soak up marinade for 15 min.
  4. Using a julienne peeler or mandolin, slice the carrots and cucumber into thin slices. Add to a small mixing bowl with the chopped romaine.
  5. Make a quick vinaigrette (or use bottled), whisk together, drizzle a little in the bowl, and gently toss
  6. Make the guacamole (avocado, salt, pepper, garlic) in a small bowl and chill in the fridge.
  7. Make the sriracha mayo (vegenaise and sriracha)  in a small bowl and chill in the fridge.
  8. Preheat a grill or a grill pan on the stove to medium heat. Spray with non-stick olive oil spray. Grill the mushrooms for 5-7 minutes on each side or until they are nicely charred on both sides.
  9. Grill or warm the burger buns or artisan bread.
  10. To assemble the burgers: Place a dollop of sriracha mayo on the bottom bun. Place the mushroom cap on top. Add the caramelized onions and then the roasted bell pepper. Add the cucumber slices, carrot sticks, and chopped romaine. Slather guacamole on the top bun and place on top of the mushroom burger.

Serve with a salad or baked sweet potato fries and corn on the cob. So good! The sriracha mayo is a great dip for the fries too!