In a container, combine chicken legs with soy sauce, cooking wine, oyster sauce, sugar, and white pepper. Marinate for at least 2 hours (or overnight for best results).
Heat oil in a large pan over medium-high heat, add the marinated chicken legs, skin-side down, and pan-fry until golden brown. Flip and sear the other side.
Pour in the remaining marinade and water (adjust the amount of water if needed). Add ginger slices and spring onion. Baste the chicken with the sauce, then cover the pan with a lid and simmer over low heat for 15 minutes. (Check frequently to prevent boiling dry.)
Once the chicken is cooked,turn off the heat and let it rest, covered for a further 5 minutes.
Serve the chicken with steamed rice and spoon the sauce from the pan over the top. Enjoy!