1. Place Portabellas, onions and vinaigrette in a large zip top bag. Let marinate for at least 30 min. Reserve marinade, if grilling.
2. If grilling: Pre-heat grill. Once hot, grill Portabella gill side down for about 5-7 min., turn over and cook for another 5-7 min. or until juices begin to accumulate in the cap. Simultaneously, wrap the onions in foil and grill. Remove the onions when the Portabellas are done.
3. Drain and reserve excess juices from the mushrooms and onions. Plate the Portabella cap gill side up. Layer slices of onion, tomato and basil leaves on top of the Portabella cap. Sprinkle each stack with 1/4 of the goat cheese and fresh herbs; drizzle with reserved marinade and serve warm.
* If microwaving: Place the mushrooms (gill side up) and the onions on a large, microwaveable plate. Cover and microwave for 3 min. Let rest 30 seconds, then carefully remove plate and uncover. Drain excess juices and reserve.
Plate the Portabella cap gill side up. Layer slices of onion, tomato and a basil leaf on the Portabella and microwave for 45 seconds. Sprinkle each stack with 1/4 of the goat cheese and fresh herbs, drizzle with reserved juices and serve warm.
Recipe and photos courtesy of the Mushroom Council and mushroominfo.com