Sauté onion, garlic, carrot, and celery in pan drippings in a large saucepan over low heat until vegetables are tender. Add flour; cook over medium heat, stirring constantly, 5 minutes or until roux is the color of a copper penny. Gradually add 3 cups broth, stirring until well blended. Stir in bay leaf and thyme. Cook, uncovered, over medium heat 15 minutes.
Add remaining 1 1/2 cups broth; cook an additional 20 minutes, stirring occasionally.
Add wine and tomato sauce; cook 5 minutes. Strain sauce through a sieve; discard vegetables and bay leaf. Serve sauce hot with roast beef or veal.