This turned up in one market today.
Artemesia japonica.
鸡肉菜/雞肉菜 (Mand: jī ròu cài; Cant: gai1 juk6 coi3), literally and inexplicably "chicken meat vegetable"'.
This is closely related to the plant in the previous post, but is sold as a leaf vegetable for stir frying or using in hot pots. It is bitter, which may be why this site rates it as only 1/5 edible. I guess they don't like bitter. Folks around here do, including me. I'd give it 3/5.