Sauce: Heat oil in saucepan. Add onion and garlic; saute for 5 minutes, or until softened. Add tomatoes, thyme, bay leaves, olives and capers; simmer, uncovered, over medium heat 15 minutes. Remove and discard bay leaves.
Preheat oven to 350 degrees F.
Coat broiler proof baking dish with nonstick cooking spray. Place fish in single layer in baking dish. Bake for 10 minutes.
Remove dish from oven. Increase oven temperature to broil. Spoon sauce over fish. Broil fish 3 to 4 inches from source of heat for 5 minutes. Serve immediately.