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Air Fryer Portobello Mushroom Burger

Air Fryer Portobello Mushroom Burgers

5 from 2 votes
Author: Laurie Fleming
Prep Time: 5 minutes
Cook Time: 9 minutes
30 minutes
Total Time: 44 minutes
Servings: 4 Servings

Description

Juicy air fryer portobello mushroom burgers with a balsamic-pesto marinade and a 5-minute pesto mayo. The mushrooms come out tender in the middle with caramelized edges, the brioche bun gets a quick toast, and the whole thing is on the table in under 15 minutes once the marinade is done. Naturally vegetarian and easy to make vegan — this is the meatless burger that actually tastes like a burger.

Ingredients 

For the mushrooms and marinade

  • 4 large portobello mushroom caps, cleaned and stems removed
  • ¼ cup balsamic vinegar
  • 2 tablespoons olive oil
  • 1 tablespoon basil pesto, store-bought or homemade
  • ½ teaspoon kosher salt
  • ¼ teaspoon black pepper

For the pesto mayo

  • ¼ cup mayonnaise, use vegan mayo for a plant-based version
  • 1 tablespoon basil pesto

For serving

  • 4 brioche buns, or whole wheat, sesame, or gluten-free buns
  • 4 slices tomato, ripe
  • 8 basil leaves, fresh
  • 4 slices provolone, mozzarella, or Swiss cheese (optional)
  • 1 cup baby arugula , or butter lettuce, optional

Instructions

  • Make the marinade. In a small bowl, whisk together the balsamic vinegar, olive oil, pesto, salt, and black pepper until fully combined.
  • Marinate the mushrooms. Place the cleaned portobello caps in a zip-top bag or shallow dish. Pour the marinade over them, seal or cover, and toss to coat. Let them marinate on the counter for 30 minutes, flipping the bag once or twice so both sides absorb the marinade.
  • Preheat the air fryer to 370°F (188°C) for about 3 minutes while the mushrooms finish marinating.
  • Air fry the mushrooms. Place the portobello caps stem side down (gill side up) in a single layer in the air fryer basket, making sure they aren't touching. Cook at 370°F for 7 to 9 minutes, until the caps are tender all the way through and the edges look glossy and caramelized. Do not flip — the gills hold the marinade and natural juices.
  • Add cheese (optional). During the last minute of cooking, open the basket, place a slice of cheese on each mushroom, and close the basket to finish cooking. The residual heat will melt the cheese.
  • Make the pesto mayo. While the mushrooms cook, stir the mayonnaise and pesto together in a small bowl.
  • Toast the buns. Remove the mushrooms and tent with foil. Place the buns cut-side up in the air fryer and toast at 370°F for 1 to 2 minutes, until lightly golden.
  • Build the burgers. Spread pesto mayo on both halves of each bun. Place a portobello cap gill side up on the bottom bun, top with a tomato slice, 2–3 basil leaves, and any optional toppings. Close the burger and serve immediately.

Equipment

  • Air Fryer
  • Cooking Spray
  • Parchment Paper, optional
  • Zip-top plastic bag or shallow dish (for marinating)
  • Small whisk
  • Small mixing bowl (for the pesto mayo)
  • Tongs or Spatula

Notes

NOTES

Choose the biggest mushrooms you can find. Portobellos shrink about 20% in the air fryer. A cap that looks slightly larger than your bun raw will fit perfectly once cooked.
Wipe, don't wash. Clean mushrooms with a damp paper towel. Running water makes them absorb moisture, which dilutes the marinade.
No parchment liners. Mushrooms release a lot of liquid as they cook. A liner traps that liquid underneath and steams the mushrooms instead of letting them caramelize.
No flipping needed. Cooking stem side down lets the gills act as a little bowl that holds the marinade — flipping pours all that flavor out.
Single layer only. If your basket is small, cook in batches. Stacked mushrooms steam each other and turn out soggy.
Make it vegan. Use vegan mayo for the sauce and skip the cheese. The mushroom and marinade are already plant-based. Check your buns — most brioche contains egg and butter, so swap to a standard wheat or vegan bun.
Make it gluten-free. Use gluten-free buns and confirm your pesto is gluten-free (most are, but check the label).
No air fryer? Roast the marinated mushrooms on a foil-lined sheet pan at 400°F for 15 to 20 minutes, stem side down, until tender. You won't get quite as much edge caramelization, but the flavor is still excellent.
Storage: Store cooked mushrooms (no bun) in an airtight container in the fridge for up to 3 days. Don't store the burgers assembled — the bun will go soggy.
Freezing: Wrap cooled mushroom caps individually in plastic wrap, then place in a freezer bag. Freeze for up to 3 months. Thaw overnight in the fridge before reheating.
Reheating: Reheat in the air fryer at 350°F for 4 to 5 minutes. Skip the microwave — it turns the cap rubbery.

Nutrition

Serving: 1ServingCalories: 652kcalCarbohydrates: 47gProtein: 17gFat: 45gSaturated Fat: 17gPolyunsaturated Fat: 7gMonounsaturated Fat: 9gTrans Fat: 0.03gCholesterol: 163mgSodium: 986mgPotassium: 439mgFiber: 2gSugar: 6gVitamin A: 1434IUVitamin C: 5mgCalcium: 225mgIron: 2mg