Brassica juncea ssp. tsatsai

Zha cai ([ʈʂâ tsʰâɪ]; 榨菜), also romanized as Cha tsai, is a type of pickled mustard plant stem originating in Chongqing, China. The name may also be written in English as cha tsai, tsa tsai, jar choy, jar choi, ja choi, ja choy, or cha tsoi. In English, it is commonly known as Sichuan vegetable, Szechwan vegetable, or Chinese pickled vegetable, although all of these terms may also refer to any of a number of other Chinese pickles, including the several other types in the Sichuan province itself....read more on Wikipedia.