2 Tbsp olive oil
2 cups finely chopped onions
2 Tbsp minced fresh ginger root
2 tsp chili powder
1-1/2 tsp ground cumin
1-1/2 pounds red-skinned sweet potatoes (yams; about 2 medium), peeled, cut into 1/2-inch pieces
2 cups orange juice
2 Tbsp minced garlic
2 15- to 16-ounce cans black beans, rinsed, drained
2 chipotle chiles in adobo, chopped
1 red bell pepper, chopped
Kosher salt and fresh black pepper, to taste
Toppings (optional): sour cream, avocado slices, orange wedges
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, approximately 10 minutes.
Stir beans, chipotles and bell pepper into sweet potato mixture. Cover and simmer for 15 minutes. Season to taste with salt and pepper. (Can be made 6 hours ahead. Cover and refrigerate. Rewarm over low heat before continuing, stirring occasionally.) Top with sour cream, avocado and orange, if desired.