Although you can use fresh mushrooms, the dried mushrooms are better because their smokey flavor enhances this soup. The chicken is stir fried first to give it a richer flavor. This soup tastes even better when made one day and eaten the next.
Cut the chicken into 1/2 inch cubes. Put them in a bowl together with the rice wine or sherry and 1 tbsp of soy sauce and let the mixture stand for 10 minutes.
Soak the mushrooms in warm water for 20 minutes. Then drain them and squeeze out the excess liquid. Remove and discard the stems and finely shred the caps into thin strips.
Bring the stock to a simmer in a large pot. Drain the marinade into the stock, reserving the chicken cubes. Add the mushrooms, scallions, ham and soy sauce. Continue to simmer the soup.
Meanwhile, heat the oil in a wok or large skillet. When it is hot, stir fry the chicken cubes over high heat until they are nicely browned. This should take about 5 minutes. Drain them on paper towels and then add them to the soup. Simmer together for 5 minutes, and the soup is ready to serve.