In a large mixing bowl, combine pepper, light soy sauce, fish sauce, and sesame oil. Stir and coat the duck and marinate for 30 minutes. Bring a fry pan to medium heat, add oil, then sear and brown the duck breasts skin-side down for 3 minutes. Remove and set aside.
Place some foil in a wok, add green tea, sugar, rice grains, cassia bark, and star anise. Place a wire rack in the wok and cover.
Turn heat to high until the wok begins to smoke. Now add the duck breasts skin-side up and reduce the heat to medium. Cover then allow to smoke.
Turn off heat and allow the duck to rest in the wok for a further 5 minutes.
Thinly slice the breasts, garnish with a combination of spring onions, chile, and coriander.