In 3-quart saucepan, heat onion, chili powder, salt, cumin, garlic and tomato juice to boiling.
Reduce heat; cover and simmer 5 minutes.
Stir in water, lentils, tomatoes and chiles.
Heat to boiling.
Reduce heat; cover and simmer 20 minutes.
Stir in corn.
Cover; simmer 10 minutes.
Stir in zucchini.
Cover; simmer about 5 minutes longer or until lentils and zucchini are tender.