Carefully crack each egg, separating the yolks and whites into two bowls. Set aside. If you can only find salted duck yolks, substitute the egg white with ½ cup water and ¾ teaspoon salt.
To a shallow dish (ideally a heatproof one you can also steam the pork in), add the ground pork, ginger, cornstarch, granulated sugar, white pepper, five spice powder, Sichuan peppercorn powder, oyster sauce, water, Shaoxing wine, sesame oil, and the egg whites.
Mix everything with chopsticks or a rubber spatula until the mixture is emulsified. Stop only when the meat mixture resembles a uniform sticky, smooth paste. Stir in the water chestnuts and scallions.
Let marinate for 30 minutes or more. If needed, transfer the meat to the final heatproof shallow bowl for steaming.
Cut each of the duck egg yolks in half. Evenly distribute them, round side up, on top of the meat patty. Set up your steamer, and bring the water to a boil.
Place the dish inside the steamer, cover, and steam for 20 minutes. Then, turn off the heat. Let sit (don’t remove the cover) for another 5 to 10 minutes. Garnish with chopped scallion and/or cilantro and serve with plenty of steamed rice!