Remove and discard giblets and neck from chicken. Rinse chicken with cold water; pat dry. Trim excess fat. Starting at neck cavity, loosen skin from breast and drumsticks by inserting fingers, gently pushing between skin and meat.
Combine soy sauce, ginger, garlic, and broth in a large heavy-duty zip-top plastic bag. Add chicken; seal and marinate in refrigerator 4 to 8 hours, turning bag occasionally. Remove chicken from bag, reserving 1/2 cup marinade.
Preheat oven to 375°.
Place chicken, breast side up, on the rack of a broiler pan or roasting pan. Insert meat thermometer into meaty part of thigh, making sure not to touch bone. Bake at 375° for 1 hour and 10 minutes or until thermometer registers 180°. Cover chicken loosely with foil; let stand 10 minutes for chicken to reabsorb juices. Discard skin.
Add 1/2 cup reserved marinade to drippings in pan (you'll have about 1/4 cup drippings), scraping pan to loosen browned bits. Pour marinade mixture into a small saucepan; bring to a boil, and cook 5 minutes. Stir in sesame oil. Cut chicken into quarters. Drizzle with sesame mixture. Sprinkle with onions.