I've used this recipe for years....unfortunately I've forgotten the original source. It's a great dish to offer at a barbecue instead of the same tired old veggie burger. The marinade is very tart and makes a lovely grilled portabella sandwich, but it would also be delicious sliced and placed on top of a nice leafy green salad. I'm posting the recipe as copied onto a piece of paper years ago, but you'll notice the dressing instructions are incomplete - sorry! I usually just grill or broil these and eat them on a bun with some red onion, lettuce, and Vegenaise (vegan mayo), if available.