In 1-gallon resealable food-storage plastic bag, mix dressing, lemon peel and lemon juice. Add halibut; seal bag and turn to coat. Refrigerate no more than 6 hours to marinate, turning bag once or twice.
When ready to cook halibut, heat gas or charcoal grill. When grill is heated, lightly oil grill rack. Remove halibut from marinade; discard marinade. Place halibut on gas grill over medium heat or on charcoal grill over medium coals; cover grill. Cook 10 to 14 minutes, turning once, until fish flakes easily with fork. Garnish with lemon slices and fresh greens, if desired.