Grilled Portobello Burgers with Avocado (Printer-friendly)

Marinated grilled portobello caps topped with creamy avocado, tomato and crisp lettuce for a hearty vegetarian burger.

# What You Need:

→ Mushrooms & Marinade

01 - 4 large portobello mushroom caps, stems removed and gills scraped
02 - 3 tablespoons extra-virgin olive oil
03 - 2 tablespoons balsamic vinegar
04 - 2 teaspoons soy sauce or tamari for a gluten-free option
05 - 2 garlic cloves, minced
06 - 1 teaspoon dried oregano
07 - 1/2 teaspoon smoked paprika
08 - Salt, to taste
09 - Black pepper, to taste

→ Burger Assembly

10 - 4 burger buns (use gluten-free buns if required)
11 - 1 ripe avocado, peeled and sliced
12 - 4 tomato slices, about 1/4 inch thick
13 - 4 lettuce leaves (romaine or iceberg)
14 - 1/2 red onion, thinly sliced
15 - 4 tablespoons mayonnaise or vegan mayonnaise
16 - 2 teaspoons Dijon mustard

# How to Make It:

01 - In a small mixing bowl, whisk together the olive oil, balsamic vinegar, soy sauce, minced garlic, dried oregano, smoked paprika, salt, and black pepper until emulsified.
02 - Brush the marinade over both sides of each portobello cap, ensuring even coverage; let the caps rest for 10 to 15 minutes while you preheat the grill or grill pan to medium-high.
03 - Place the mushrooms on the hot grill, cap side down first, and cook 4 to 5 minutes per side until tender and lightly charred; baste once with remaining marinade if desired.
04 - Lightly toast the burger buns on the grill for 30 to 60 seconds per side until golden and warmed through.
05 - Spread mayonnaise and Dijon mustard on the bottom half of each bun, layer with a lettuce leaf, a grilled portobello cap, a tomato slice, avocado slices, and red onion; finish with the top bun.
06 - Serve the assembled burgers right away with your preferred side dishes so the avocado is fresh and the mushrooms remain juicy.

# Cooking Tips:

01 -
  • It’s the secret star of any mixed-crowd barbecue, with flavors so deep even carnivores reach for seconds.
  • The quick marinade infuses those big mushrooms with smoky, tangy, utterly addictive goodness each time.
02 -
  • Once, I let the mushrooms sit too long in the marinade and they lost their shape—set a timer for the best texture.
  • I discovered toasting the bun is non-negotiable; it stops everything from sliding around and keeps your burger sturdy.
03 -
  • If the mushrooms look a little shriveled after grilling, brush with a tiny bit of extra olive oil before serving—it brings back gloss and flavor.
  • Stacking the avocado between the tomato and mushroom prevents it from slipping out with every bite.
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