Pour 1/2 cup Wish-Bone Light® Italian Dressing over mushrooms in shallow baking dish or large resealable plastic bag; turn to coat. Cover, or close bag, and marinate 30 minutes.
Remove mushrooms from marinade, discarding marinade. Grill or broil mushrooms 5 minutes or until mushrooms are tender; thinly slice.
Toss hot orzo with tomato and garlic. Let stand covered 10 minutes. Stir in remaining ingredients. Season, if desired, with salt and freshly ground black pepper and garnish, if desired, with Parmesan cheese curls. Chill, if desired.