Heat the olive oil in a large saucepan over medium heat. Add the sausage and cook about 5 minutes, until no longer pink.
Add the celery, onion, and garlic and sauté 3 to 5 minutes, or until tender. Stir in the broth, ½ cup of water, tomato, bay leaf, Italian seasoning, and tomato paste. Bring to a boil. Reduce the heat to a simmer.
Stir in the zucchini and pasta, cook uncovered, for 7 to 10 minutes, or until the pasta is al dente. Discard the bay leaf. Season with salt and pepper to taste.
Notes
For a heartier soup, add additional vegetables. Diced carrots, cut green beans, and spinach are great additions.Spice up the flavor by sprinkling on some red pepper flakes. You can also top off with some freshly grated Parmesan cheese.