Portobello Mushroom Burgers

Ingredients

• Mustard (4 tablespoons)
• Mayonnaise (4 tablespoons)
• Red onion (1, sliced)
• Tomato (1, sliced)
• Lettuce (4 leaves)
• Hamburger buns (4)
• Olive oil (2 tablespoons)
• Garlic (2 cloves, minced)
• Soy sauce (2 tablespoons)
• Balsamic vinegar (2 tablespoons)
• Portobello mushrooms (4 large)

Instructions

1. In a small bowl, whisk together the balsamic vinegar, soy sauce, minced garlic, and olive oil to make the marinade.
2. Remove the stems from the portobello mushrooms and place them in a shallow dish. Pour the marinade over the mushrooms, making sure they are well coated. Let them marinate for at least 15 minutes.
3. Preheat the grill to medium-high heat.
4. Grill the marinated mushrooms for about 5 minutes per side, or until they are tender and slightly charred.
5. While the mushrooms are grilling, toast the hamburger buns on the grill for a minute or two until they are lightly toasted.
6. Spread mayonnaise and mustard on the bottom half of each bun. Top with a grilled portobello mushroom, lettuce, tomato slices, and red onion slices.
7. Place the top half of the bun on the assembled burger and serve immediately.