Combine the ground beef, 1/2 teaspoon salt, Shaoxing wine and 1 teaspoon cornstarch in a small bowl. Mix well and marinate while preparing the rest of the ingredients.

Bring a small pot of water to a boil. Add the ground beef and turn to lowest heat. Break apart the beef as much as you can, until the beef has just turned a pale color, 1 to 2 minutes. Drain the beef and discard the boiling water. Break apart any large beef pieces as needed.

Heat the chicken broth and ginger in a medium pot over high heat until bringing to a boil. Add the mushroom and tofu. Simmer for 3 minutes, until the mushrooms are cooked.

Combine the 1/4 cup of cornstarch with 1/4 cup water in a small bowl, stir to dissolve completely. Pour the slurry into the pot. Stir immediately to mix well to thicken the soup.

Turn to low heat. Slowly pour in the egg white so it goes into the pot in a very thin stream. Once you’ve added all the egg whites, stir gently to break apart the eggs into thin ribbons. Add the cooked beef into the soup and stir to mix well. Turn off the heat. Add the scallion, salt and white pepper. Stir to mix well. Serve hot.