Return the meat to the pan and toss. Add the green onions and toss again. Next add the five-spices, sugar, vinegar, and cornstarch mixture and continue to st ir fry until the sauce is somewhat thickened and glossy (May need to add additi onal teaspoon of cornstarch to stir fry to reach desired consistency). Add salt and pepper to taste. If you want a more distinct sweet and sour flavor add mor e sugar and vinegar at this time. Also, if you want the dish hotter, gradually add dried red pepper flakes a bit at a time until the desired conflagration is obtained.