How to Make It
In a large soup pot, heat the olive oil. Add the onion, fennel and thyme and cook the vegetables over moderately high heat, stirring occasionally, until the onion and fennel are softened, about 8 minutes. Stir in the tomato paste and season with salt and pepper. Cook, stirring, for 5 minutes. Add the water and the tomatoes and their juices and bring to a boil. Simmer the soup over moderate heat, stirring occasionally, until the liquid is reduced by one-third, about 30 minutes. Discard the thyme.
Transfer half of the soup to a blender and puree until smooth. Return the puree to the pot. Serve the soup with Pan-Fried Potato Croutons, Fennel-Orange Gremolata and diced Fontina cheese.