3 portobello mushrooms
1/4 cup canola oil
3 tablespoons chopped onion
4 cloves garlic, minced
4 tablespoons balsamic vinegar

1) Clean mushrooms and remove stems, reserve for other use. Place caps on a plate with the gills up.
2) In a small bowl, combine the oil, onion, garlic and vinegar. Pour mixture evenly over the mushroom caps and let stand for 1 hour.
3) Grill over hot grill for 10 minutes. Serve immediately.