If you've ever stood in front of the vast selection of Chinese pickled vegetables in an Asian grocery store, wondering which one is the right kind for the dish you want to make, I completely sympathize. (If you haven't, you're missing out!) There are almost as many different kinds of pickled and preserved mustard greens and vegetables as there are vegetables, and each region has a different twist on how to preserve them.
Some of the cookbooks I've read lump them all together as "pickled mustard greens" and "pickled vegetables." Dunlop goes to great lengths in her Sichuan and Hunan cookbooks to disguish between zha cai, ya cai, suan cai, and pao cai*, while also mentioning several other variants along the way. I have never located any of the preserved mustard greens in clay jars that she talks about in the Ann Arbor area. (Which doesn't mean they don't exist here, so if you've seen pickled mustard greens in clay jars let me know!)
(* Remember the "pao" character from my chili introduction, which means "pickled." So pao cai is literally "pickled vegetable.")
Dunlop tries to distinguish between them by calling them pickled mustard greens, preserved mustard greens, and preserved mustard tuber (zha cai), and then confuses the matter by translating suan cai as "pickled mustard greens" in her Sichuan cookbook but as "preserved mustard greens" in her Hunan cookbook. This confusion aside, she offers some of the most detailed explanations for the different preservation methods I've found in English language Chinese cookbooks. My main problem is that I can't find jars that use the exact same language she uses. Most of the jars I've looked at come with the characters for suan cai or other characters entirely, and the English translation is almost always "pickled mustard greens," thus making it difficult to tell just which kind of mustard green is actually in the container. So what is a person to do?
When I first went to find "ya cai" (what the recipe I wanted to make called for), I asked one of the store owners at Tsai Grocery. She spoke little English, we spoke little Chinese. I thought if I showed her the characters for ya cai, that would make it a snap. She studied the characters a long time and took her time surveying the shelves before making her suggestions. This one seemed to be her preferred option. She was very clear that these greens needed to be cooked a little rather than eating them straight out of the package. This packaging matches the description that Dunlop gives for pao cai in her Hunanese cookbook. (click on the image to see a larger version)
This jar was the second recommendation from the lady at Tsai Grocery. They are pre-chopped and pickled in a brine of water and soy sauce, sugar, chili oil, and sesame oil. A close inspection will reveal red flecks of chili. (This brand also has MSG and other preservatives.) She told us that these pickled mustard greens can be eaten straight out of the jar, if desired. For example, you can serve a bit on top of a bowl of rice or chopped up and sprinkled as garnish over a noodle dish. (She says they're great with Dan Dan noodles. I'd guess she means the kind of Dan Dan noodles with the creamy sesame-peanut sauce, which is not the version of the dish I posted earlier.)
This is another jar of pickled mustard greens. The characters are different. While the English is "pickled mustard greens," the Chinese characters say something else entirely which I haven't been able to fully translate. (The first character has to do with the concept of "opening.") However, the chopped vegetable looks very similar to the second picture above, and the ingredients are nearly identical but with less preservatives (like citric acid) and no MSG. (I like this jar because the brand translates as "Comrade Food," which I find amusing.)
Some final thoughts on shopping for pickled mustard greens:
First, you won't necessarily find all the options in the same section of the grocery store. I saw pickled mustard greens in large plastic tubs in the chilly fresh produce section of Hua Xing, plastic-sealed packages piled in a box near the end of an aisle, and a long stretch of shelf filled with glass jars of pickled mustard greens and other vegetables. So make sure to look not just on the shelves for sealed glass jars, but also in the vegetable section and in coolers for preserved vegetables.
Second, don't be overwhelmed by all the choices. I try not to get too hung up on getting the exact kind of pickled greens for a recipe, otherwise I would never try cooking some dishes for fear of having the wrong item! I suspect that a lot of the different pickled greens can work as substitutes for each other. Perhaps an expert would find them quite different, but so far as I can tell, they all have the salty sour taste characteristic of pickled vegetables. So, until I get better information on how to distinguish the different types, I'm not going to worry about it! The first one pictured above is a very common type of pickled mustard greens that would work for most cooking situations. You can also look for "Tianjin [or Sichuan] preserved vegetables," which can substitute for pickled mustard greens.
I would love to hear others' experiences with and brand recommendations for mustard greens and other Chinese pickled vegetables.