Combine first 8 ingredients in cooking bag. Massage the ingredients from the outside of the bag to ensure that the sugar, onions, ginger, and chili pepper are distributed throughout the liquid.
Add the chicken to the cooking bag and seal the bag tightly. Rotate the bag to coat the chicken thoroughly with the marinade.
Refrigerate the bagged chicken for at least 3 hours or overnight, turning bag occasionally.
Preheat oven to 350 degrees.
Set bag with chicken (breast side up) on a cookie sheet. Cut 5 small vents in the top of the bag.
Bake until chicken is tender and brown, about 1 hour and 15 minutes.
Open bag and pour juices into a bowl. Cut the chicken into serving pieces and arrange on a platter.
Skim fat from the top of the pan juices. Pour a bit of juice over the chicken pieces. Garnish with green onions.
Serve with rice, passing remaining juice separately.