Instructions
Prevent your screen from going dark as you follow along.
-
In a large saucepan, heat the butter and vegetable oil over medium heat. Add the onion and sauté until softened and golden, about 10 minutes.
-
Add the tomatoes, basil, thyme, and black pepper. Bring the mixture to a simmer, and cook for 10 minutes.
-
In a small bowl, combine the flour and broth, whisking until smooth, and add this mixture to the soup, stirring constantly.
-
Cover and simmer slowly for 25 minutes, stirring occasionally.
-
If you've used diced tomatoes, purée the soup in a blender or food processor, or use a hand blender. If you've used tomato purée, there's no need to blend; the onion bits will give the soup a bit of body.
-
Return the soup to the stove, and set it on a burner over low-to-medium heat.
-
Stir in the baking soda (the soup will foam up briefly; don't worry, but be sure it's in a big enough pot), the sugar, milk, and salt. Heat to a bare simmer, stirring constantly. Serve hot.
