Mix the oil, teaspoon of soy sauce, teaspoon of vinegar, ginger, garlic and honey or brown sugar in a bowl, then add the beef strips to a bowl. Leave it to marinate for a few minutes so the beef doesn’t dry out when you cook it. If the beef is quite a tough cut, leave it to marinate for longer in the fridge (you can do this the night before or morning of the day you plan to cook it).
Place a wok over a high heat. You’ll know it’s hot enough and ready for stir-frying when you flick a little water into the pan and it immediately evaporates. Add the marinated beef and cook it for a few minutes, tossing and stirring it constantly so none of it burns. Remove the beef from the pan. Add a little more oil if the wok is dry, add the mushrooms and broccoli and fry for a minute or two, tossing frequently, then add the chilli and spring onion. Stir a couple more times, then taste. Season the stir-fry with sesame oil, soy sauce and vinegar to bring out all the flavours of the dish and serve hot, garnished with lots of sesame seeds on egg or rice noodles (if you wish).