In a saucepan, combine the first eight ingredients; bring to a boil. Reduce heat; simmer, uncovered, for 30 minutes.
Discard bay leaf; press mixture through sieve and set aside. In a large saucepan, melt butter; stir in flour until smooth. Gradually stir in milk. Bring to a boil over medium heat, stirring constantly; cook and stir for 2 minutes. Reduce heat. Gradually stir in tomato mixture until smooth; heat through.