Grilled Portobello Burger with Avocado
Meaty portobello mushrooms marinated in sesame oil, soy sauce, balsamic vinegar, and miso, then grilled and stacked on toasted buns with creamy guacamole, fresh tomato, curly lettuce, and sprouts. A satisfying vegetarian burger with umami depth and bright citrus notes.
Ingredients
- 2 portobello mushrooms, whole
- 2 burger buns, halved
- 1 tablespoon sesame oilneutral oil or olive oil1:1Full guide →
- 1 tablespoon soy sauce
- 1 tablespoon balsamic vinegar
- 1 tablespoon misoadditional soy sauce1/2 tablespoontags:umami
adds:gluten
- 2 avocados, pitted and peeled
- 1 red onion, sliced or diced
- 2 cloves garlic, minced
- lemon juice, from 1/2 lemon
- salt, to taste(optional)
- black pepper, to taste(optional)
- plant-based mayonnaise, for spreadingvegan mayo or hummus1:1
- curly lettuce
- 1 tomato, sliced
- sprouts, for garnish
Instructions
- 1
Combine sesame oil, soy sauce, balsamic vinegar, and miso.
- 2
Coat portobello mushrooms with marinade and set aside.
- 3
Cut, peel, and halve avocados, mash flesh with a fork, then mix with garlic, lemon juice, red onion, salt, and pepper to make guacamole.
- 4
Place marinated portobellos on grill and cook for 5-8 minutes per side.
- 5
During the last two minutes of grilling, halve the buns and grill them to crisp.
- 6
Assemble burgers starting with bottom bun half, spread with mayonnaise, layer curly lettuce, tomato slices, grilled portobello, and guacamole.
- 7
Top with bun half and sprouts, then serve immediately.
Tips
Grill buns in the final minutes to prevent them from drying out while staying warm.
Prepare guacamole just before assembly to minimize browning.
Good to Know
Guacamole best made fresh, but store covered with plastic wrap directly on surface up to 2 hours. Cooked mushrooms keep refrigerated up to 3 days.
Marinate portobello mushrooms up to 4 hours ahead. Prepare guacamole base ingredients but don't mash until assembly time.
Serve immediately after assembly while buns are still warm and mushrooms are hot.
Common Mistakes
Do not over-grill portobello mushrooms to avoid drying them out; 5-8 minutes per side is sufficient.
Do not assemble burgers far in advance to avoid soggy buns from mayonnaise and juices.
Substitutions
adds:gluten