Years ago, when I lived in the DC metro area (Montgomery County, MD and Fairfax County, VA), and when I traveled to the left coast at least twice a month, I used to frequent oriental groceries. Each time I would go to a store, I would bring home something that I had never seen or used or eaten before and figure out what to do with it.
I was such a habitué at a market in Annandale, VA (you longtime DC denizens surely remember Kam Sen market; now some other market) that the Chinese grandmothers would ask me what to do with certain foodstuffs.
Somewhere along the line, I stumbled on big tubs of various vegetables, preserved in salt and chile pepper. It was great to be able to buy the exacty quantity of various mustards, radishes, and turnips that I needed for my dishes. By comparing the Chinese characters on the labels on the tubs and those on various cans, I came to realize that many of these same items were also available in cans and small crocks.
This was years before the labels featured pictures of the contents as does the photo above. My only clue was to look for the cans labeled in German Präserviertes Gemüse, which translates as Preserved Vegetable in English. After years of playing with seeds from oriental markets, I now know that what's in the can is known in English as Chinese Thick-Stemmed Mustard and while it has very tasty mustard greens when young, its real beauty shines forth once the stem starts to bulge and it is harvested and salted.
I just love this stuff. I am reminded of it today because my daughter brought home four ravenous teenage girlfriends last evening, quite conveniently at 6:30pm. I had to scramble for dinner and with very little in the fridge, I went for the always crowd-pleasing fried rice. I just love the little salty, spicy bits of this mustard in my fried rice and so apparently did the my guests, if they tasted anything at all while inhaling dinner.