Heat the oil in a wok and fry garlic until it goes lightly brown then add the onion and fry for 3 minutes.
Add the chilli, ginger, broccoli florets, sweetcorn and courgettes and continue to fry for a further 5 minutes.
Add the pak choi and the water chestnuts and toss to mix in for a further 2 minutes then add the soy sauce, lime juice and a few more drops of the oil.