In a bowl, whisk together soy sauce, sherry, oyster sauce, grated ginger, sesame oil, brown sugar, and five-spice powder to create the marinade.
Add chicken pieces to the marinade, guaranteeing all pieces are well-coated. Cover and refrigerate for 2-3 hours or overnight.
Cut parchment paper into 6-8 inch squares, making sure you have enough for each chicken piece.
Place a slice of ginger and some green onions on each parchment square.
Add one marinated chicken piece on top of the aromatics on each parchment square.
Gather the corners of the parchment and fold the sides like an envelope, creating a secure packet that seals in the chicken.
Steam the packets in a steamer for 20 minutes, or bake at 375°F (190°C) for 20 minutes until chicken is fully cooked.
Serve immediately while hot, allowing guests to unwrap their own packets at the table.