Soak the dried shiitake and lily flowers (if using) by in hot water for an hour (or more)

Set the stock in a pan to heat up.

Cut the ginger into fine slivers. Trim off and discard the stalks of the soaked mushrooms and thinly slice the caps. To the same for the fresh shiitakes, cutting the caps into wide strips.  

Cut the oyster mushrooms lengthwise into similar thin strips.

Gently pull apart the clumped enoki mushrooms.

Cut the tofu and/or chicken (if using) into strips a similar size to the mushrooms.

Heat oil in a woke over high flame.  Add the ginger and sizzle for a few seconds until fragrant. Then add the mushrooms and lily flowers and stir fry until the mushrooms are half-cooked and begin to color (a few minutes).

Pour in the heated stock and bring to a boil.

Add the tofu and chicken (if using) and stir gently. 

 Season the soup with the soy sauces and salt to taste (it should be fairly salty).

Reduce the heat to a simmer. Add the vinegar and pepper and simmer for around 30 seconds.  Remove from heat and stir in sesame oil.  

To serve: Carefully ladle or pour the soup from the wok into a deep pot or tureen.  Scatter the spring onions over the soup and serve.