Pork with Ginger and Spring Onion

Ingredients (serves 2):
300g pork, cut into thin strips - Edit: I forgot to mention that I tend to use pork loin for this dish, and either rump or sirloin for the beef version. Slice the meat thinly for the marinade to infuse the meat thoroughly and for quick cooking.
4 stalks of spring onions, cut into inch-long sections on the diagonal
5-6 white button or shitake mushrooms, sliced (optional)
1 inch piece of ginger, peeled and sliced
Oil for cooking

Marinade:
1 tbsp Chinese rice wine (or dry sherry)
1 tbsp light soy sauce
1 tsp cornflour
A dash of white pepper

Seasoning:
1 tbsp Chinese rice wine (or dry sherry)
1 tbsp oyster sauce
1 tbsp light soy sauce
1/2 tbsp dark soy sauce (for colour, optional)
1/2 tbsp sesame oil
4 tbsp water
2 tsp corn flour, dissolved in 2 tbsp water

Make it!
1. Marinade the pork and set aside in the refrigerator for a few hours or overnight for best result.
2. Combine all the seasoning ingredients (except for the last cornflour mixture) in a bowl. Heat a wok or heavy based pan on medium-high heat. Add in some cooking oil and heat until the oil is hot but not quite smoking. Stir fry the ginger and white parts of the spring onions very quickly for about 30 seconds.
3. If using, add the mushrooms and stir fry for 1-2 minutes. Then add the pork and stir fry briskly until the meat is about 70 percent cooked, which should take only a couple of minutes. Add the green parts of the spring onions, pour the seasoning ingredients into the pan and mix evenly.
4. Stir in the corn flour mixture at the end and simmer on low heat for about a minute to thicken the sauce. Dish out and serve immediately, making sure to avoid overcooking the beef. The strong flavours of this dish go well with plain rice rice.