1Heat oil in 4-quart Dutch oven over medium heat. Cook onion in oil, stirring occasionally, until tender.
2Stir in water; heat to boiling. Stir in tortellini and potatoes. Heat to boiling; reduce heat. Cover and simmer 13 to 15 minutes, stirring occasionally, until potatoes are tender.
3Stir in remaining ingredients. Heat to boiling; reduce heat. Simmer uncovered 5 minutes.