Crush Sichuan peppercorns and transfer into a bowl. Crush garlic cloves. Shred green and red cabbages. Heat 2 non stick pans and pour 2 tbsps oil in each. Add both the cabbages to one pan and add salt. Add garlic to the other pan.
Chop red chillies. Sauté garlic till brown and then add red chillies and continue to sauté. Add chicken and mix well and continue to sauté. Add Sichuan peppercorns, red chilli sauce, oyster sauce and dark soy sauce and mix. Cook till the chicken is cooked. Mix cornflour with ½ cup water. Transfer the cabbage into a serving dish.
Add ½ the cornflour mixture and salt to the chicken and mix well. Cook till the sauce thickens. Arrange chicken over the cabbage. Drizzle sesame oil and serve hot with steamed rice.