Heat oil in heavy large pot over medium heat. Add onions and sauté until tender, about 10 minutes. Add ginger, chili powder and cumin and stir 2 minutes. Add sweet potatoes, orange juice and garlic and bring to boil. Reduce heat, cover and simmer until sweet potatoes are almost tender, about 10 minutes. Stir beans, poblano chilies and bell pepper into sweet potato mixture. Cover and simmer until chilies are tender, about 15 minutes longer. Season to taste with salt and pepper. (Can be made 6 hours ahead. Cover and refrigerate. Rewarm over low heat before continuing, stirring occasionally.) Divide stew among 4 bowls. Top with sour cream, avocado and orange, if desired.
*Serve w/ corn bread
**People have added chicken, extra veggies (carrots, celery, etc), and canned tomatoes