Grilled Portabella Mushrooms With Balsamic Marinade - cooking recipe

Ingredients

MARINADE
1 cup balsamic vinegar
2 tablespoons olive oil
1 teaspoon dried basil
1/4 teaspoon kosher salt
1/4 teaspoon white pepper (I just use freshly ground black pepper)
2 garlic cloves, minced
6 portabella mushroom caps (about 1 1/2 lbs.)
cooking spray
DRESSING
1 tablespoon olive oil
1 1/2 cups sliced onions
1/4 cup mayonnaise
1 teaspoon bottled minced roasted garlic
6 whole wheat kaiser rolls or 6 hamburger buns
6 curly lettuce leaves
6 slices tomatoes

Preparation

Combine first 6 ingredients in a large zip-top plastic bag. Add caps to the marinade. Seal and marinate in fridge up to 24 hours.
Prepare grill or broiler.
Remove caps and discard marinade. Place caps on grill rack or broiler coated with spray. Cook 5 minutes or until tender.
Heat oil over medium-high heat. Add onion. Cover and cook ten minutes or until golden, stirring frequently. (at this point I assume you mix the onions and garlic into the mayo, but I've never actually used this step).
Assemble grilled portabella sandwiches with one cap per bun, plus any lettuce, mayo, tomato, onion, or other garnish that you like. Or slice the portabellas into strips and enjoy as a topping for a mixed green salad with onion, tomato, etc.