Add remaining oil to pan; cook onions, ginger and garlic over medium heat, stirring occasionally, for 4 to 6 minutes or until softened. Add sweet potato, carrot and curry powder; stir to coat. Stir in chicken broth. Bring to a boil. Reduce heat to medium; simmer uncovered for 15 to 20 minutes or until sweet potatoes and carrots are almost tender. Stir in chicken; simmer another 5 to 10 minutes or until chicken is cooked through and vegetables are easily pierced with a fork.