Ingredients

3 portobello mushroom caps
1/4 cup olive oil
1/2 medium onion chopped
3 cloves garlic minced
4 tablespoons balsamic vinegar
Mozzarella cheese slices (optional)

Directions

Briefly rinse the mushrooms and drain or wipe the mushrooms with a damp cloth

Place caps in a shallow bowl or baking dish without overlapping gill side up

In a small bowl combine the oil onion garlic and vinegar Pour the mixture over the mushroom caps Let stand for at least an hour Grill over a hot grill for about 10 minutes During the last minute or two on the grill top with slices of mozzarella cheese if desired

Serve burger-style with lettuce and tomatoes