Heat olive oil in a large Dutch oven over medium-high heat. Add onion, and sauté 4 minutes or until tender. Add water and next 7 ingredients (water through broth), and bring to boil. Cover, reduce heat, and simmer 5 minutes or until zucchini is tender.
Stir in pesto and tortellini; cover and simmer 6 minutes or until thoroughly heated and pasta is tender.