Heat oil in 3 quart non-aluminum pot over medium high heat. Add onions, zucchini, cumin, chili powder, the chipotle puree and salt. Stir well and cook until softened, stirring often, about 7-10 minutes.
Add broth, corn, beans, tomatoes and tomato paste. Heat to boil, reduce heat; simmer, partially covered, stirring occasionally, 30 minutes. Simmer, uncovered, to reduce slightly, about 15 minutes.
Add water if chile is too thick.
Top with cilantro. Pass sour cream and sliced green onions separtely.