Heat your wok or skillet over medium heat, then add the black sesame oil along with the sliced ginger and cook for 2 minutes.
Turn up the heat to high, and sear the chicken legs (in batches if needed) until browned on all sides. Once the chicken legs are nicely browned, turn the heat back down to medium and add in rice wine, rock sugar, and water.
Cover and simmer over medium heat for 30 minutes. The soup should be bubbling, but not boiling.
The soup is ready once the chicken legs are tender. Season with salt to taste and garnish with scallions when serving.