Step 1Trim any parts of ginger that are not firm and smooth. Slice into 1/4-inch thick pieces. Set aside. Trim root ends of green onions. Leave about 2 inches of green parts and cut white and green parts into thin slices. Set aside.
Step 2Combine soy sauce, Sherry and sugar in bowl. Set aside.
Step 3Heat peanut oil in 12-inch nonstick skillet over medium-high heat. Hold palm of your hand 1 inch above oil; if you can feel heat, oil is ready. Add chicken and ginger pieces, spreading in single layer. Use a fork to move pieces occasionally so they don't stick to bottom of skillet. Brown chicken and ginger pieces, about 5 minutes each side.
Step 4Reduce heat to medium-low and pour sauce evenly over chicken and ginger. Cover and cook until no pink remains around chicken bone (test for doneness by cutting a slit to the bone), 8 to 10 minutes.
Step 5Remove chicken pieces and arrange on platter, sprinkled with green onions. Strain sauce and skim fat. Return sauce to skillet. Cook over medium heat, reducing by one-fourth, 2 to 3 minutes. Serve with chicken, if desired. Accompany with jasmine rice.