1. Cut the mushrooms into slices, the spring onion into rings and the pak choi into quarters lengthwise.
  2. Heat 1 tbsp of oil in the wok and fry the steaks until medium cooked in 5 min. Turn over halfway.
  3. Take the steaks out of the pan and let them rest on a plate under aluminium foil.
  4. Heat the rest of the oil and stir fry the mushrooms, half of the spring onions with the five spice for 3 min. Add the pak choi and stir fry for 2 min.
  5. Add the black bean sauce with the water and sugar and stir fry for 1 min.
  6. Season to taste with pepper. Serve with rice.