For my after McKingses victory supper, I am having a portabello mushroom "burger". What I am doing is taking a large prorto top, 5-6 inches in diameter, splashing some extra virgin olive oil, (I'm assuming they come from really ugly olives), on it, a dash or two of garlic powder, and a dash or 5 of old bays seasoning. Grilling it on an oak fire, topping it off with some sharp cheddar or pepper jack cheese. (Haven't decided yet). I will set it all on an onion roll and garnish it with my favorite burger toppings.
These things are the bomb. You will not even realize you are not eating a beef burger. I even do this in the winter with just my cast iron grill on the stove.
You will not be disappointed.