In a large pot over medium high heat, saute the diced onion in our EVOO, about 3-4 minutes.
Add in the minced garlic and cook it for another minute.
Add in the salt, pepper, and 2 cans of whole tomatoes.
Using a potato masher, mash the tomatoes until they are all broken up.
Add in the bay leaf, brown sugar, and chicken broth and bring the mixture to a boil.
Once the soup is boiling reduce the heat to medium low and simmer for 10 minutes.
Remove the soup from the heat. Remove the bay leaf and discard.
Pour half of the soup into a blender or food processor and process until smooth.
Strain the soup and repeat the process with the second half.
Return the strained soup to the pot and stir in the balsamic vinegar.
Bring the soup to a simmer and cook for several more minutes.
Serve the soup immediately topped with chives.