1
Heat the oil in a large pot over medium heat.
2
Add onions, carrots, celery, peppers and garlic and cook for 10 to 12 minutes, until vegetables are softened but not browned.
3
Add chipotles, oregano, cumin, chili powder and salt. Stir to blend.
4
Add tomatoes and 4 cups water.
5
Gently simmer over low heat, uncovered, for 45 minutes.
6
Add beans and simmer an additional 30 minutes.
7.Garnish individual bowls with green onions or sour cream, if desired.