First prep the beef by laying some cling film over it on a chopping board then smashing it thinner using either a rolling pin or mallet. Using a really sharp knife, and working against the grain of the meat, slice it into thin slices holding the blade at a 45 degree angle. Trim off any fat.

Create a slurry by combining the cornflour with a bowl of cold water and then lay the beef strips into it so they're submerged fully. Set aside and leave for 30 minutes. This process will tenderise the meat.

Boil some water and add it to a small-medium saucepan and add the Pak choi to blanche it gently. Heat a wok over a high heat and spray the base liberally with Coconut oil. Once nice and hot add in the beef strips and the whites of the spring onion plus half of the red chilli. Stir fry until the juices of the meat come out and the excess cornflour which will thicken and coat the beef lightly. Season with a pinch of salt.

Next add in the light soy and fry for 30 seconds whilst stirring. Add a dash of water in and turn the heat down slightly and bring to a simmer. Once the water has reduced by half add in 1/2 tbsp of teriyaki sauce and toss to coat the beef. Turn off the heat and leave to keep warm whilst you assemble the donburi. Remove the Pak choi from the hot water and pat dry gently with kitchen towel.