Sprinkle in flour and cook, while stirring, for 3 minutes. Gradually add chicken broth, followed by tomatoes, sugar, and all the herbs and seasonings.
Reduce heat and gently simmer for about 20 minutes or until vegetables are tender.
If you don't have fresh basil, you can substitute dried basil. The rule of thumb seems to be that when using dried herbs instead of fresh, you use 1/3 the amount. Which would mean you'd need to add about 1 ½ tbsp. of dried basil. That seems like kind of a lot though, so you could always start with less and then add more to taste.