1In deep 12-inch skillet, heat oil over low heat 5 minutes. Sprinkle chicken with salt and pepper; place in hot skillet. Cover chicken with yellow and green onions. Increase heat to medium. Cook 10 minutes; turn chicken. Cook 10 minutes longer or until golden. Reduce heat to low; cook 5 minutes longer. Turn; cook 5 minutes. Remove chicken from skillet. Place in large pot or Dutch oven; set aside.
2Continue heating skillet over low heat. In medium bowl, stir flour, soy sauce, 2 cups of the hot water and the onion powder with wire whisk or fork until smooth.
3In hot skillet, cook flour mixture over medium heat, stirring constantly with wire whisk or fork, until mixture boils and thickens. Gradually stir in remaining 1 1/2 cups hot water until smooth.
4Pour gravy over chicken in large pot. Heat to boiling; reduce heat to low. Cover and simmer 1 hour, stirring occasionally. (Gravy may stick to pot.)