2 cups onions, chopped
2 teaspoons olive oil
1/3 cup peanut butter
6 cups sweet potatoes (not yams), peeled and cut into 1 inch cubes
1 tablespoon ground cumin
1/4 teaspoon salt
1/2 teaspoon pepper
1/4 teaspoon cayenne pepper
2 (15 1/2 ounce) cans garbanzo beans, undrained
2 (14 1.2 ounce) or 1 (32 ounce) cans low-sodium vegetable broth
1 (28 ounce) can diced or crushed tomatoes, undrained