Cut the pork into 5 cm long strips - less than 1 cm wide
Mix together the marinade ingredients in a bowl then add the pork and stir it well to coat all the strips. Leave for about 10 minutes while you prepare the other ingredients.
Heat the wok on a high heat and, when it's good and hot, add the groundnut oil.
Add the garlic & leek, stir-fry for ½ minute, then add the pork and stir-fry for about 3 minutes.
Add the remaining ingredients and continue stir-frying for another 3 minutes
Garnish with some more coriander or other green herb, if you like, and serve with boiled rice.