#A very warming soup, this is a favorite in winter in Peking. Add chili sauce and vinegar to suit your taste.#
Trim any fat from the pork and slice it into shreds about 2 inches long and less than 1/2-inch thick.
Soak the mushrooms in boiling water until softened. Place the pork in a large pot with the shrimp and stock. Bring to the boil and then reduce the heat to allow to simmer gently for 4-5 minutes.
Add all the remaining ingredients except for the egg, and cornstarch and water mixture. Cook a further 1-2 minutes over low heat.
Remove the pan from the heat and add the egg gradually, stirring gently until it forms threads in the soup.
Mix a spoonful of the hot soup with the cornstarch and water mixture and add to the soup, stirring constantly.
Bring the soup back to simmering point for 1 minute to thicken the cornstarch. Serve immediately.
Vary the amount of chili sauce to suit your own taste.
Hot and Sour Soup is very versatile. Substitute other ingredients such as chicken, crabmeat, bean sprouts, spinach or green cabbage.
The soup must be hot enough to cook the egg when it is added, but not so hot that the egg sets immediately.