Chop the onion and garlic into small pieces. Fry them with the bacon in the butter until translucent. Add the tomato paste and toast briefly. Mash the canned tomatoes with a fork and add their sauce to the saucepan. Add the stock, bay leaf and herbs, season with pepper and simmer for 30 minutes.
Take out the bay leaf and puree the soup. Then stir in the cheese and sour cream, heat until the cheese has melted and season with pepper.