This Portobello mushroom burger nixes the bread and presents a low-carb option for people looking for a delicious vegetarian meal. Roasted Portobello mushroom caps are piled high with zucchini, onion, tomatoes, avocado, spinach and cheese. You are free to explore alternate combinations. If I have olive tapenade on hand, I like to mix it with some mayonnaise to create a lovely sauce to accompany the sandwich.
Portobello Mushroom Sandwich
8 large Portobello mushroom caps, cleaned and gills removed
4 cups fresh spinach
2 garlic cloves, finely minced
1 cup shredded mozzarella cheese
1 vine-ripe tomato, sliced into 1/3-inch-thick slices
2 to 3 jarred roasted red peppers, cut into slices
1 medium zucchini, ends trimmed, halved, and sliced lengthwise
1 small red onion, peeled and sliced into 1/4-inch-thick rounds
1 avocado, sliced
kosher salt and freshly ground black pepper, to taste
Step 1: Preheat oven to 400 degrees Fahrenheit.
Step 2: In a bowl, toss the cleaned mushroom caps in olive oil, just enough to coat, and season with salt and pepper. Place all eight caps, gill-side-down, on a large baking sheet lined with parchment pepper. Roast the mushrooms for 15 minutes.
Step 3: At the same time, roast the zucchini and red onion on a separate baking tray lined with parchment paper. Toss the vegetables lightly in olive oil and season with sea salt and black pepper. Bake alongside the mushrooms for 20 to 25 minutes or until tender.
Step 4: Meanwhile, heat a teaspoon or two of olive oil in a non-stick skillet or frying pan over medium heat. Add the garlic and cook until fragrant, about 30 seconds. Add the spinach and season with salt and pepper. Cook the spinach until the leaves just begin to wilt. Remove from heat and set aside.
Step 5: Remove mushrooms from the oven and very carefully flip them so the underside of the cap is facing upwards. Distribute the spinach evenly between 4 of the 8 mushroom caps and sprinkle with mozzarella cheese. Place back in the oven for another 5 to 7 minutes until cheese has melted.
Step 6: Assemble the sandwiches. On the mushroom cap with the spinach and cheese, layer the roasted onions and zucchini, red peppers, fresh tomato, and avocado slices. Top with the remaining mushroom cap.