Grilled Portabella Mushrooms

4 medium-sized (about 12 ounces) fresh portabella mushrooms
2 tablespoons butter
2 teaspoons minced garlic
2 tablespoons balsamic vinegar
1/4 teaspoon salt
dash ground black pepper
1 tablespoon chopped fresh basil or parsley

Preheat outdoor grill or boiler. Separate mushroom caps from stems; set caps aside. Coarsely chop stems (to measure 1 cup).

In a medium saucepan melt butter. Add chopped stems and garlic; cook, stirring frequently, until stems are tender, 5 to 6 minutes. Stir in vinegar, salt and black pepper; remove from heat. Transfer to the bowl of a food processor; process until finely chopped; set aside.

Place mushroom caps, rounded side up, on a grill or rack in a broiler pan. Grill or broil 4 inches from heat until mushrooms are hot, 2 to 3 minutes. Turn; spread each mushroom with 1/4 of the chopped mushroom stem mixture; cook until mushrooms are tender, 4 to 5 minutes longer. Serve on toasted rolls with sliced tomato and arugula or watercress, if desired.

Makes 4 servings
Source: Mushroom Information Center