Lost in Translation: “Old sour water makes the best pickled mustard greens”

One of the most elegant recipes for lacto-fermenting mustard greens, requires an ingredient you probably don’t have. Old sour water.

Sounds disgusting right? It’s not. Old sour water (老酸水), also known as old crock water (老坛水), is the highly acidic liquid saved from previous ferments.

In early 2013, a women in a Guiyang market taught me to how to lacto-ferment mustard greens. In Sichuan and Guizhou, mustard greens are not called jiecai (芥菜) or xuelihong (雪里蕻)Instead, they are known as qingcai (青菜). Auntie Zhang has been using qingcai to make “suancai” (酸菜) for over 30 years, and she swears, “old sour water makes the best pickled mustard greens.” This is her recipe.

You will need your very own “old sour water”. When Auntie Zhang first taught me this recipe, she gifted me a plastic coke bottle filled with her own mustard green ferment juice for my Beijing-based pickle experiments. Here in the states, I’ve found sauerkraut juice (the kind teeming with lactic-acid bacteria) works as a good substitute for your first batch of pickled mustard greens. My first batch tasted a bit like baijiu and Sichuanese peppercorn, but by the second or third ferment, it smelled and tasted like Guiyang Auntie’s pickled mustard greens. I used my kraut juice from the North China sauerkraut, refrigerating it in glass jars these past 4-5 months. If you have a cup of sauerkraut juice in your fridge, you’re ready for this recipe.

If you don’t have old crock water, check out Taiwan Duck’s method to start from scratch.

Length of ferment:
1 day to months

Large sink or basin for washing greens
Kitchen scale
1-liter canning jar (I use Le Parfait style flip-top jars)
Small glass bowl or porcelain tea cup

Step 1: Sun-dry the mustard greens until limp

1kg Chinese mustard greens (typical varieties available in Atlanta’s Asian groceries include large leaf, small leaf, and xuelihong)

1. Wash the greens. Use clean water to wash your mustard greens of dirt and debris. Remove any damaged leaves.
2. Dry the greens until limp. Hang the mustard greens on a clothes line in full-sun from morning to night. If not limp by evening, leave out over night and through to the second day. I’ve found they become limp and lose 50-60% of their weight with only one day in intense sunlight.
3. Inspect the greens. Remove any yellow or dehydrated leaves.

Step 2: Make taomishui 淘米水 (water from rinsing rice)

4 cups water1/4-1/2 jasmine rice

1. Place rice in a bowl.
2. Pour in water, stir. Use your hand to cloud the water, moving the rice about until the water is a milky white. Remove the rice and set aside the now cloudy water for the next step.

Step 3: Pack the canning jar

limp mustard greens
1 cup old crock water
3-4 cups taomishui
2 tablespoons salt

1. Pack the jar with mustard greens.
2. Pour the old crock water into the jar.
3. Pour the taomishui into the jar. Stop pouring, approximately 1 inch from the jar’s lip.
4. Add the salt. Close the jar, sealing it and shake to mix the ingredients. Reopen the jar.
5. Submerge the greens. Place the small bowl or tea cup on top of the mustard greens to keep submerged.
6. Close and seal the jar.

Step 4: Ferment!
1. Place in a cool dark place.
2. After 1-2 days, taste the greens for level of sourness. I’ve left them on the counter up to a week before moving the jar to the refrigerator for storage



Lacto-fermented mustard greens are used in soups and stir-fries. A quick search of the English language internet came up with these results:

For those of you with Fuchsia Dunlop’s books, don’t forget about her chicken soup and fish soup in “Land of Plenty” and her fava bean recipe in “Revolutionary Chinese Cookbook.” All three recipes use lacto-fermented mustard greens. When you’re improving a fried rice or a noodle soup, this version of suancai makes a great addition. Auntie Zhang is partial to suancai in fish soups.

And don’t forget to save your old sour water!


6 thoughts on “Lost in Translation: “Old sour water makes the best pickled mustard greens”

  1. By dehydrated, do you mean leaves that are 100% dried out as opposed to 50-60%? It’s also interesting how most fermented goods develop a distinct and better taste if one reuses the same “mother” batch, like sourdough bread, kombucha, etc.!

    • By dehydrated I mean completely dried or shriveled. When I made my last batch two weeks ago, the sun here in Georgia was intense, no cloud cover to soften the UV. Within 6 hours of direct sunlight, my mustard was wilted. Some of tips and even a few full leaves were yellow and dry. There was so little moisture that rubbing the leaf would disintegrate it in between your fingers. So, if the mustard leaf is supple and healthy looking, use it. If there are leaves that look dead, too dry or heavily discolored, they should be removed.

    • I’m not entirely conversant when it comes to the underlying science, but it seems to serve the same function adding sugar does. If I had to guess, the taomishui 淘米水 has sugars that help lactic acid bacteria quickly proliferate in the water.

    • Yes, but only with stems, not with the leaves. In the past, when I cook collards, I have removed the stems and cut those up and placed them in the old sour water. They taste fine, but they do cause a problem. Unlike mustard greens, as the collard stems ferment, the water grows more and more slimy. There must be something in the stems that forms a scum when interacting with the acidity or as its digested by the bacteria. To eat them, I’d just rinse off the slime.

      That said, the lacto-fermented collard stems tasted quite good. They were much sweeter than mustard greens but still had its signature lacto-fermented sour flavor. When you bite the stems, you get a good crunch. In the two or three batches I’ve done, the collard’s fibrous stems hold up well for long periods (3-4 months) at fridge temps (34F-36F) in old sour water.

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