Put the sesame oil in a pan with a little oil and add the chilli flakes, if using. Fry for 1 minute, then add the spring onions and ginger, and cook for 1 minute. Add the chicken and prawns, and toss briefly. Scrape everything to one side of the pan. Break the egg into the other side, stir a little, cook until set, then break up into pieces. Mix in the beansprouts, add the rice and cover the pan until the rice warms through. Season with soy sauce, sprinkle with coriander and a little chilli sauce if you like.