Preheat the oven to 180°C.
Line a wok with foil and top with tea leaves and brown sugar.
Heat the wok until smoking and smoke the duck breast for 12 minutes.
Transfer the duck to a baking sheet and roast until pink in the middle.
Boil chopped sweet potato in salted water until tender.
Drain and mash the potato with soy sauce and lime juice.
Heat vegetable oil in a large saucepan for frying.
Coat onion rings in beaten egg and flour.
Fry the onion rings in hot oil until golden-brown and drain.
Slices the duck and serve over the mash with onion rings on top.