Heat the flavourless oil in a wok on a high heat, then add the spring onions, chilli, ginger and garlic
Cook for a few minutes shaking the pan often so that they don’t burn, then add the pak choi, prawns and bean sprouts
Cook until the prawns have changed from grey to pink and the pak choi wilted
Season with the sesame oil, soy and lemon
Serve sprinkled with the sesame seeds.