Cook onion in butter in a Dutch oven over medium-high heat, stirring constantly, for 5 minutes or until tender. Reduce heat to low; add flour, stirring until smooth. Gradually add broth; cook over medium heat, stirring constantly until thickened and bubbly. Add tomatoes and next 7 ingredients; stir well. Bring to a boil. Cover and reduce heat. Simmer 30 minutes. Remove and discard bay leaf.
Spoon part of tomato mixture into container of an electric blender; cover and process, until smooth. Repeat procedure with remaining tomato mixture. (Note: May be made ahead of time and refrigerated up to this point.)
To serve, ladle hot soup into individual serving bowls. Top each with Herbed Croutons. Yield: 4 servings.
Trim and discard crusts from brea d slices. Spread butter over brea d; sprinkle with cheese and basil. Cut each slice into 4 squares; cut each square into 2 triangles. Place on an ungreased baking sheet; bake at 325° F for 20 minutes, or until croutons are dry and browned.