Wash and dry the tomatoes, then chop them roughly. Try to squeeze out excess water and seeds. Peel onion, garlic and carrot. Finely slice onion and garlic cloves and grate the carrot.
In a soup pot, heat olive oil, then add onions and lightly fry them until translucent. Add grated carrots and garlic, stir-fry for about a minute or two, until the carrots tenderize. Then, add in chopped tomatoes and a dash of balsamic vinegar, stir well and let it cook down for a few minutes, stirring regularly.
Add vegetable stock, bay leaves and season to taste with salt & pepper. Bring to a boil, then lower the heat and cook for about 15 minutes.
When the tomatoes are cooked, remove the pot from heat, then remove the bayleaves and blend into a smooth soup with a stick blender.
Roughly chop basil leaves and add to the soup for taste and garnish, add a teaspoon of sour cream and serve.