- Cut bottom 7cm off the lemongrass stem, and slice very thinly (keep the remaining portion to flavour soup stocks if you like)
- Marinate beef in lemongrass, corn flour, fish sauce and soy for at least 1 hr.
- Heat 1 tbsp oil in a wok, add watercress and 2 tbsp water and toss for 1 min. Arrange on a plate and keep warm.
- Heat remaining oil in the wok, add beef and stir-fry for 3-4 mins or until cooked. Add sweet chilli sauce, stir through, and serve over watercress.
- Garnish with coriander and sliced chilli.
- Serve with Jasmine rice.