If you don't want to make many gallons of this soup, here's a version scaled down for the home cook, adapted from Serious Eats. I use Mexican crema instead of cream, tempered with a bit of the hot soup before adding. Make sure to use dried basil, it won't work well at all with fresh because of the cooking time. Although this allegedly makes 4 servings, I got 6 generous bowls of soup.
- In a large, heavy saucepan, heat the olive oil over medium-high heat until shimmering. Add carrot and onion and cook until beginning to soften, 10 minutes, then add basil and cook until vegetables are completely soft, about 5 minutes more.
- Add tomatoes and broth, bring to a boil, then reduce heat and simmer 30 to 45 minutes.
- Allow the soup to cool somewhat, then purée until smooth in a blender or food processor or using an immersion blender. Strain the purée before returning to the pot for a smoother texture.
- Add cream or tempered crema little by little over over low heat until desired texture is reached. Do not boil it! Season to taste with salt and pepper, and serve warm.