Without adding any oil, toast the rice in a non-stick frying pan, stirring constantly until golden brown. Blitz the rice and chilli flakes in a food processor, set aside.
Heat the oil in the same pan, stir fry the chicken for approx. 5 mins., reduce the heat. Add the lemongrass, fish sauce, lime juice and ginger.
Mix the spring onions, shallots and celery in with the chicken, simmer for a further 2 mins.
Mix the cucumber, herbs and rice & chilli mixture in with the chicken salad. Serve on lettuce leaves.