Step 1

If you prefer to use beef flank instead, use a cleaver to finely mince the meat. In a large heat-proof bowl, combine the meat with the marinade ingredients and let them marinate for about 30 minutes when you prepare other things

Step 2

Add the chicken broth, water, chicken powder, sugar,pinch of salt, pepper, ginger slices, and mushrooms to a medium-sized pot. Bring to a boil and then lower the heat to let it simmer for about 5 minutes. Remove the ginger

Step 3

Ladle some of the broth over the beef in a heat-proof bowl and break and separate the meat as you mix so the meat won't clump together when you put it into the soup

Step 4

Pour this back into the soup pot and cook until the meat is no longer pink. Some scum may arise, scoop them off. Have a taste and adjust seasoning to your preference

Step 5

Combine potato starch with water to form a paste. Add this to the soup as you stir. The soup will thicken slightly. Then slowly drizzle in the lightly beaten egg whites as you slowly stir the soup. Turn off the heat. Add sesame oil and cilantro leaves just before serving. Serve the soup while it's still warm