The secret to this creamy, delicate, fresh tomato soup is using a sweet onion, which cuts the acidity of the tomato.
3 tablespoons unsalted butter
3/4 cup minced sweet onion, such as Vidalia
1 1/2 pounds tomatoes—peeled, seeded and chopped, with juices
1 teaspoon tomato paste
2 cups low-sodium chicken broth
1 basil sprig
Salt
Freshly ground pepper
12 thin baguette slices, toasted
1/4 cup plus 2 tablespoons freshly grated Parmigiano-Reggiano cheese
In a large saucepan, melt the butter. Add the onion and cook over moderate heat, stirring, until softened, about 5 minutes. Add the tomatoes and their juices, along with the tomato paste and cook, stirring, for 5 minutes. Add the broth and basil and season with salt and pepper. Simmer until the tomatoes are broken down, about 15 minutes. Discard the basil and puree the soup until smooth.
Preheat the broiler and arrange the baguette toasts on a baking sheet. Sprinkle with the cheese and broil just until melted, about 30 seconds. Serve the soup with the cheese toasts.
