Wash shark's fin in warm water and strain. Keep aside.
Bring chicken feet and chicken breast to boil over high flame for 5 minutes, reduce flame to low and simmer for 20 mins. Strain the stock.
Bring chicken stock to boil with salt, add shark's fin, shredded chicken meat and crab meat. Simmer for 3 mins, thicken with cornflour.
Lastly add in egg white. Remove and serve with black vinegar and pepper.