Ingredients

(Serves 4)

• 4 large portobello mushroom caps, 5 inches in diameter (about 16 ounces total)
• 1/3 cup balsamic vinegar
• 1/2 cup water
• 1 tablespoon sugar
• 1 garlic clove, minced
• 1/4 teaspoon cayenne pepper, optional
• 2 tablespoons olive oil
• 4 whole-wheat buns, toasted
• 4 slices tomato
• 4 slices red onion
• 2 bibb lettuce leaves, halved

Directions

Clean mushrooms with a damp cloth and remove their stems. Place in a glass dish, stem (gill) side up.

To prepare the marinade, in a small bowl whisk together the vinegar, water, sugar, garlic, cayenne pepper and olive oil. Pour over the mushrooms. Cover and marinate in the refrigerator for about 1 hour, turning mushrooms once.

Prepare a hot fire in a charcoal grill or heat a gas grill or broiler. Away from the heat source, lightly coat the grill rack or broiler pan with cooking spray. Position the cooking rack 4 to 6 inches from the heat source.

Grill or broil the mushrooms on medium heat, turning often, until tender, about 5 minutes on each side. Baste with marinade to keep from drying out. Using tongs, transfer the mushrooms to a plate.

Place each mushroom on a bun and top with 1 tomato slice, 1 onion slice and 1/2 lettuce leaf. Serve immediately.