Remove the tofu from the packet and wrap it in some kitchen paper to soak up excess moisture.
Cut the stems from the shiitake mushrooms and discard them, then slice the caps into 2-3mm (⅛") thick strips.
The stems also freeze very well and can be used to make stock
Peel the ginger and cut it into batons as finely as you can.
Peel the garlic cloves and slice them as thinly as possible.
Trim and clean up the spring onions, then cut the white end into 1cm (½") long lengths and finely shred the green ends, keeping the white and green bits separate.
Mix the soy sauces, Chinkiang vinegar, sesame oil, crispy chilli oil, white pepper and MSG together with the cornstarch and set aside.
Place the egg in a bowl and lightly beat it.
Cut the tofu into 5mm (¼") thick batons.
Heat a wok over a high heat and when it is hot, add the oil, garlic, ginger and white parts of the spring onion and stir fry for 45-60 seconds.
Throw in the mushrooms and stir fry for 60-90 seconds.
Pour in the vegetable stock and bring to a boil.
When the stock is boiling, add the spicy soy sauce mix and cook until the stock thickens a little. This will take a minute or two.
Whilst whisking, slowly pour in the beaten egg.
Add the tofu and the green parts of the spring onion (keeping a little back for garnish), and cook for a final 60 seconds.
Notes
This like many Asian dishes really flies at a rate of knots so make sure everything is shopped mixed and prepared before you get started for the perfect dish.