Take boneless chicken leg meat and keep in refrigerator for half an hour after mixing with egg white and cornflour. Take out and deep fry until light brown; then keep aside. Heat oil in wok and add chopped garlic and fry until slightly brown and aroma comes out. Then add some bean sprouts and crushed black pepper followed by dark soy sauce, oyster sauce, apple cider vinegar and white vinegar. Add bok choy whole leaves and onion petals and stir quickly. Add the chicken followed by salt and sugar and mix well. Add chicken stock or water mixed with cornflour to the wok and mix well. Let the broth thicken slightly and adjust the seasoning quickly. Remove from heat and serve immediately with steamed or fried rice.