In a heatproof shallow dish (a glass or ceramic pie plate works well), add the chopped shallots, oyster sauce, minced garlic, salt, cornstarch, chicken bouillon, sand ginger powder, sugar, grated ginger, and white pepper. Stir to combine into a paste.
Rub the chicken legs thoroughly with the marinade until they are coated, and arrange in the dish so they are lying flat. Cover and marinate for at least 2 hours or overnight for best results.
When you’re ready to cook the dish, take the marinated chicken legs out of the refrigerator for 1-2 hours. This helps ensure your chicken legs cook evenly.
Carefully place the dish in a pre-heated steamer with boiling water, cover, and steam over medium-high heat for 20-25 minutes, depending on the size of your chicken legs. You can use a meat thermometer to ensure the internal temperature has reached 160-165°F/71-74°C.
Top the chicken with chopped scallions if desired, and serve with plenty of white rice and a stir-fried leafy green vegetable on the side.