DRIZZLE 2 Tbsp. dressing over fish in shallow dish. Refrigerate 30 min. Meanwhile, combine beans, tomatoes, onions, basil and 2 Tbsp. of the remaining dressing.
HEAT grill to medium heat; cover grate with foil. Place fish, skin-sides down, on foil.
GRILL 10 to 15 min. or until fish flakes easily with fork. Toss spinach with remaining dressing; place on 4 serving plates. Top with fish and bean mixture.
