Cut the chicken into 7.5cm/3 inch long shreds. Mix the egg white, salt and cornflour, toss in the chicken and mix well. Leave to stand for 15 minutes.
Fry the sesame seeds in a wok, or pan, in a little hot oil until golden. Remove and set aside.
Heat the remaining oil in a wok, add the chicken and stir-fry for one minute. Remove with a slotted spoon. Add the soy sauce, vinegar, chilli bean sauce, sesame oil, wine or sherry and peppercorns and bring to the boil. Replace the chicken, add the spring onions and cook for two minutes, stirring constantly. Sprinkle with sesame seeds and serve while still hot.