1. Heat the olive oil in a large pot or Dutch oven over medium heat. Add the finely chopped yellow onion and cook, stirring occasionally, until it softens and becomes translucent, about 5-7 minutes.

2. Stir in the minced garlic and cook for another minute until fragrant. Be careful not to burn the garlic.

3. Pour in the condensed tomato soup and the undrained diced tomatoes. Stir well to combine, breaking up any large pieces of diced tomato with your spoon.

4. Add the vegetable broth, dried oregano, salt, and black pepper to the pot. Bring the mixture to a gentle simmer, stirring occasionally.

5. Once the soup is simmering, add the refrigerated cheese tortellini. Cook according to package directions, usually 3-5 minutes, until the tortellini are al dente and float to the surface.

6. Reduce the heat to low. Stir in the heavy cream and chopped fresh basil. Cook for another 1-2 minutes, just until heated through, but do not boil after adding the cream, as it can curdle.

7. Taste the soup and adjust seasonings as needed. You might want a little more salt, pepper, or even a pinch of sugar to balance the acidity of the tomatoes.

8. Ladle the hot soup into bowls, garnish with extra fresh basil if desired, and serve immediately.