Heat 1 teaspoon of olive oil over medium heat in a large stockpot or Dutch oven.
Add the chopped carrots, onions and celery and cook for 3 to 5 minutes until veggies are soft.
Add the garlic and cook for 1 more minute.
Add the diced tomatoes and stewed tomatoes, the chicken stock, basil, dried oregano, sugar and black pepper. Put the lid on the pot, turn the heat up to "medium-high" and bring the mixture to a boil.
When the soup starts to boil, turn the heat down to "medium-low" and let it simmer with the lid on for about 15 to 30 minutes.
Blend the soup with an immersion blender, until the soup is completely smooth.
Stir in the parmesan cheese until the cheese melts.
Remove the soup from heat and stir in ¼ cup nonfat Greek yogurt.
Top with some extra fresh basil, if you have any.