Dust veggie mixture with flour and stir to combine.
Add the tomatoes, tomato paste, basil, sugar and broth. Bring soup to a simmer, then reduce heat to medium-low and allow to simmer gently for 15 minutes or until the vegetables are tender. Remove from heat. Using an immersion blender or working in batches, puree the soup leaving some texture. Stir in the milk and reheat on low without allowing to boil.
Serve in soup bowls with a swirl of fresh basil pesto and a side of mozzarella dunkers.
Notes
Total time for Mozzarella Dunkers is 1 hour 30 minutes, but can be prepared ahead and baked just before serving.