In 3-quart or larger pot, heat 2 tablespoons olive oil over medium heat. Add 2 large sweet potatoes (about 1 3/4 lb), peeled and diced; cook 5 minutes. Add 1 small yellow onion, diced, and 1 teaspoon ground allspice; sprinkle with some salt and black pepper. Cook 5 minutes. Add chicken broth; simmer 10 to 15 minutes or until sweet potatoes are tender.