Preheat oven to 400°.
Heat oil in a medium saucepan over medium heat until hot. Add green onions, pineapple, mango, bell peppers, jalapeño, and 1 teaspoon thyme; sauté 2 minutes. Add tomato purée, lime juice, 1/4 teaspoon salt, and black pepper; bring to a boil. Cover, reduce heat, and simmer 5 minutes. Remove from heat; keep warm.
Rub fish with 1 teaspoon thyme and 1/4 teaspoon salt. Place fish on a broiler pan coated with cooking spray. Spoon mango mixture evenly over fish. Bake at 400° for 20 minutes or until fish flakes easily when tested with a fork.