CUT 4 thin slices from lemon. Squeeze remaining lemon to get 1 Tbsp. juice. Mix lemon juice and dressing; brush onto flesh sides of fish. Refrigerate 30 min to marinate.

HEAT barbecue to medium-high heat. Grill lemon slices and fish, skin-sides down, 10 min. or until fish flakes easily with fork, turning lemon slices over after 5 min.

TOP fish with lemon slices and parsley.