Cut chicken into 1-inch pieces.
To prepare marinade, in bowl combine soy sauce; dry sherry, sake, or mirin; gingerroot; garlic; and sugar.
Marinate about 30 minutes at room temperature; stir once or twice.
Roll the chicken pieces in cornstarch to coat evenly (use about 1/2 cup); shake to remove excess cornstarch.
Fry chicken pieces, several at a time, in deep hot oil (365°) for 2 to 3 minutes or till golden.
Using slotted spoon or wire strainer, remove pieces and drain on paper toweling.
Keep warm while cooking the remaining chicken.
Arrange on heated serving platter.
Cut green onions in 1 -inch lengths; cut pieces into thin lengthwise strips.
Sprinkle atop chicken.