Sprinkle chicken with salt and pepper; dust with flour. Melt butter with oil in large skillet over medium-high heat. Add chicken; saute until brown, about 3 minutes per side. Transfer chicken to plate. Add ginger to skillet; stir 1 minute. Add brown sugar and mustard and stir to blend into drippings. Add orange juice and orange peel. Simmer until sauce is slightly reduced, stirring occasionally, about 8 minutes. Return chicken and any accumulated juices to skillet. Simmer 3 minutes. Turn chicken over and add green onions. Simmer until chicken is cooked through and sauce is thick enough to coat spoon, about 3 minutes longer. Season sauce with salt and pepper. Transfer chicken and sauce to platter.