Navajo Stew

This is a recipe from the Moosewood Restaurant cookbook, and we've loved it since we had it with our friends in Asheville last winter. It's hearty, healthy, and spicy -- perfect for cool fall and winter nights...

Navajo Stew
2 medium sweet potatoes
2 red or green bell peppers
1 large onion
4 garlic cloves, minced
2 Tbsp. vegetable oil
1 Tbsp. ground cumin
1 tsp. salt
1/4 tsp. black pepper
1 (15 oz.) can of tomatoes
1 Tbsp. canned chipotles in adobo sauce
1/2 cup chopped fresh cilantro
1 (15 oz.) can of butter beans of black beans, drained
flatbread (tortillas, lavash, or pita)
plain yogurt, sour cream, or Cilantro Yogurt Sauce

Preheat the oven to 450 degrees F.
Lightly oil a baking sheet.
Peel the sweet potatoes and cut into 1-inch cubes.
Stem and seed the peppers and cut into 1-inch pieces.
Peel the onion and cut it stem end to root end into thin wedges.
In a bowl, toss the vegetables with the garlic, oil, cumin, salt, and pepper.
Spread on the prepared baking sheet and roast in the oven for about 10 minutes. Stir and continue to roast for another 10 to 15 minutes, until the sweet potatoes are tender but not mushy.
While the vegetables roast, puree the tomatoes, chipotles, and cilantro in a blender until smooth. Set aside.
When the vegetables are tender, put them into a 2- to 3-quart baking dish, stir in the tomato-cilantro sauce and the beans, and return to the oven until hot, about 10 minutes.
A few minutes before serving, warm the bread in the oven. Serve the stew in bowls topped with yogurt or sour cream, with warm flatbread on the side.