Heat a large pot over medium heat with the olive oil.
Add the chopped onion and cook for 5 minutes until softened, stirring.
Next add in the garlic and stir, cooking for a minute more, then add in the salt, pepper, oregano and sugar. Stir and cook for another minute, then stir in the can of tomato paste.
Carefully pour in the tomato puree, sauce and chicken broth.
Stir together and cook for 15 minutes covered partially with a lid.
After the soup has cooked, pour in the milk and blend with an immersion blender until smooth.
Taste for seasonings and serve.
