Marinated Chicken Stir Fry

From The Wagamama Cookbook

2 chicken breasts, cut into strips
2 lemongrass stalks, very thinly sliced
2-3 red chillies, trimmed and sliced
2 garlic cloves, peeled and crushed
3 tbsp veg oil
2 tbsp fish sauce
1 small red onion, peeled and cut into strips
12 mangetout
2 handfuls beansprouts
1/2 green pepper. deseeded and cubed
1 tsp salt
1 tsp sugar
4 tablespoons salted peanuts, chopped
3 tablespoons light soy sauce
300ml water
2 tablespoons cornflour
300g steamed rice
few springs corriander, chopped

Put chicken, lemongrass, garlic, 1 tbsp oil and fish sauce in a large bowl. Mix, cover and refrigerate overnight.
Heat wok over a medium heat until hot. Add remaining oil and onion. Stir fry for 1 minute until slightly caramelised.
Add the chicken and its marinade and continue stir frying for 1 minute to seal the meat.
Add the mangetout, beansprouts and green pepper. Stir fry for a further 2 minutes.
Add salt, sugar and half the peanuts. Stir fry for a further minute.
Add the soy sauce and the water.
Mix the cornflour with 2 tbsp of water and 2 tbsp of the sauce from the wok. Combine until it forms a paste.
Add cornflour paste to the wok and toss well.
Continue cooking for a further 5 minutes until the sauce is thick and glossy.
Serve with rice, garnish with remaining peanuts and coriander.