Something like this..........only bigger!
Forgot to take a picture...we scarffed 'em down too quick.
Two large Portabella Mushrooms - sprinkle with EVOO and Red Wine Vinegar. Grill 4-5 minutes on each side. Top with two slices fresh mozzarella cheese last minute of cooking.
Sprinkle buns with EVOO and grill til toasty.
Garnish with Lettuce leaves, Tomato slices, Red sweet onion slices, Mayo and any other favorites.