Heat the olive oil in a medium-sized pot over medium heat. When hot, add the garlic and “Italian” seasoning. Stir until the garlic is fragrant and tender, about 5 minutes.
Add the tomatoes with all the juices and the miso. Stir to ensure the miso is completely dissolved and break apart the tomatoes with a spoon or spatula as desired. When the mixture reaches a boil, reduce heat to low, cover, and simmer for 7 minutes.
If you’d like to use a hand (immersion) blender, you can use it now to bring the soup to your desired consistency.
Taste the soup. If it is too sour for your taste, add the sugar or sweetener, stir well, and taste again.
Garnish with basil and olive oil as desired and serve immediately.