Pre heat oven to 300 degrees. Line 2 baking sheets with parchment paper and set aside.
In large bowl add 2 tablespoons of olive oil and Italian seasoning. Slice tomatoes in half and add to the bowl. Mix until coated with olive oil. Place tomatoes in a single layer cut side up and roasted for about 1-2 hours. The longer they are roasted the more caramelized they become.
In large pot and heat 1 tablespoon olive oil over medium high heat. Add carrots and onion and sauté for 4 minutes. Then add minced garlic, salt, pepper, and balsamic vinegar and cook for another 2 minutes. Add tomatoes and broth to desired consistency and simmer for about 10-15 minutes. Add fresh basil and stir in sour cream.
In batches add soup to a food processor or blender and puree until smooth.
Serve topped with croutons and parmesan cheese.
