Saute first 4 ingredients in margarine in a skillet over medium-high heat until tender. Stir in crushed tomatoes and tomato sauce. Cook, uncovered, over low heat 30 minutes or until thickened. Remove and discard bay leaf. Stir in 2 tablespoons parsley, 1/4 teaspoon salt, sugar, and 1/4 teaspoon pepper.
Rinse fillets and pat dry; sprinkle with remaining 1/2 teaspoon salt and 1/4 teaspoon pepper. Dredge fillets in flour. Cook fillets in hot oil in a large nonstick skillet over medium-high heat 2 to 3 minutes on each side or until fish flakes easily when tested with a fork. Transfer to a serving platter. Spoon sauce evenly over fillets; sprinkle with remaining 2 tablespoons parsley. If desired, garnish with fresh thyme and serve with green beans.