When boiling, drop the tomatoes in the water to blanch one minute, or until the skin cracks.
Quickly remove from the water, let it cool a few minutes and the skin will come right off.
Chop onions, carrots, celery and garlic using a mini food processor or chopper.
Melt butter in a large soup pot over medium heat.
Add butter until melted, then add chopped onions, carrots, celery and garlic.
Cook stirring often until soft, about 8-10 minutes.
Add chicken broth and tomatoes, stirring well.
Using a string, tie herbs together and drop into the soup.
This will make it easy to remove later.
Add salt and fresh pepper, reduce heat to low and simmer covered for 30 minutes.
Remove herbs and discard, add sour cream and blend with a hand blender until smooth. (A regular blender would work, but be sure to let the soup cool before blending and fill only halfway in the blender so it doesn't explode on you).
Ladle into bowls and top with freshly grated cheese and fresh basil.