Heat a wok until very hot. Add a tablespoon of olive oil. Coat the beef in the seasoned Cornflour and stir-fry, in batches, until crispy. Remove to a dish and keep warm while cooking the vegetables.
Add a little more oil to the wok. Add in the broccoli, mushrooms, mange-tout, red pepper, garlic and ginger and stir-fry for a couple of minutes.
Return the meat to the wok and add in the dressing ingredients. Stir to combine and continue to cook for another minute.