Grilled Portabella Mushroonms

This recipe was posted on the Addicted to BBQ discussion board.

INGREDIENTS
4 to 5 Large Portabella Mushroom Caps
Italian Salad Dressing
1 large Sweet Onion (cut into 1/4" slices, one per mushroom)
Olive Oil
Kosher Salt
Fresh Cracked Black Pepper
Your Favorite Spice Rub (optional)
Your Favorite Cheese (pepper jack, mozzarella, provolone, what ever you like)

PREPARATION:
Brush any dirt off the mushrooms, do not rinse them under water. Snap the stem out of the center of the mushroom cap. Cover the mushrooms with some Italian salad dressing and let them marinate for 15 or 20 minutes. Rub the onion slices with olive oil and then add a light coat of kosher salt and cracked pepper to both sides. If you would like a little more flavor or want to add some heat add some of you favorite rub, something like Tony Chachere's. I use Cajun Blast Steak Seasoning available at Cajun Brands on the web.

GRILL SETUP:
Set the egg up with an extended grill. This can be done with a three of fire bricks on edge set at 120 degrees apart on the fire ring if you don't have a grid extender. You can accomplish this using three carriage bolts some nuts and washers as shown on The Naked Whiz's site.

Start your lump and stabilize at 450 and then add wood for smoke if you'd like.

THE COOK:
Place the onions on the grill. Let them go for 5 minutes and then flip them using a spatula. Now add the mushrooms gill side down and let everything go for another 5 minutes. Now flip the mushrooms and put the onion on top of them. Put your favorite cheese on top and let them go for a few more minutes until the cheese melts.

These babies are absolutely awesome. Try them you'll love them.