Marinade minced beef for about 15 minutes.
Wash spinach,cut or chop until very fine.
Bring stock to boil, then add in beef, using a chopstick to loosen meat lumps. when stock boils again, add in spinach and stir well.
add in seasonings, and let boil. Add in cornstarch solution and thicken soup. Bring to large boil, then turn off heat.
immediately add in egg whites, and stir egg whites to form flakes.Serve with some pepper if desired.