Step 1: Slice chicken into thin strips and marinate with oyster sauce and pepper.
Step 2: Roll the chicken in the cornflour, then fry it and set it aside.
Step 3: In a very hot wok put oil, ginger, onion petals, and garlic and stir-fry for a few minutes.
Step 4: Add the peppers and stir-fry quickly to keep them crunchy.
Step 5: Add the crispy chicken and the hoisin sauce, stir well, and add water.
Step 6: Remove from the heat and add the coriander and onion stems.