Combine tomatoes, 1 teaspoon butter, and water in a medium saucepan. Bring to a boil; boil 10 minutes, stirring often. Add garlic, bay leaf, and thyme. Return to a boil; continue to boil until mixture is reduced to 1 1/2 cups. Remove from heat, and mash through a sieve; set aside.
Melt remaining 1 tablespoon butter in a medium saucepan; stir in flour. Cook over medium heat, stirring constantly, until lightly browned. Stir in pureed tomato mixture, 1/2 teaspoon salt, and 1/4 teaspoon pepper. Continue to cook over medium heat, stirring constantly, until sauce thickens. Set aside.
Combine egg and milk in a medium mixing bowl; stir well. Sprinkle fish with remaining salt and pepper. Dip fish in egg mixture, and roll in breadcrumbs. Melt 1/2 cup butter in a large skillet over medium heat; add fish, and fry until golden brown and fish flakes easily when tested with a fork. Drain on paper towels.
Transfer fish to a warm serving platter, and garnish with fresh parsley sprigs. Serve immediately with reserved sauce.