½ pound butter
1 pound yellow onions (about 3 medium), cut into ¼-inch dice
1 stalk of celery, cut into ¼-inch dice
1 large carrot, peeled and cut into ¼-inch dice
½ cup all-purpose flour
4 28-ounce cans whole San Marzano tomatoes
2 tablespoons garlic paste
1¼ cups chicken broth
1 tablespoon kosher salt
¾ teaspoon freshly ground black pepper
¾ cup half-and-half
1 tablespoon sugar
Salt and pepper to taste
In a large pot, melt the butter over medium-low heat. Add onions, celery and carrot and cook, stirring occasionally, until soft, about 20 minutes.
Add flour and stir until mixture is slightly thickened and pale gold, about 3 minutes; do not allow to brown.
Stir in the tomatoes and their juices, garlic paste, chicken broth, salt and pepper. Raise heat to medium until the liquid bubbles, then reduce heat to low. Simmer for 30 minutes, scraping the bottom of the pot frequently.
Stir in half-and-half. Remove from heat and purée using an immersion blender or allow to cool until no longer steaming and purée in batches in a stand blender. Return to medium heat just until heated through.
Ladle into warmed bowls, and serve with grilled cheese sandwiches