Vietnamese pickled mustard greens have a distinctive tanginess and crunch texture from lacto-fermentation which serves as a great side dish for many braised dishes.

To start our Tet or Vietnamese New Year celebration, I wanted to share a recipe that we make all year long but also an essential for this time, my mom’s dưa cải chua, or Vietnamese pickled mustard greens. For as long as I can remember, we always had a jar of pickled mustard greens in the kitchen. During Tet we eat it with thit kho (Vietnamese braised pork and eggs in coconut caramel sauce). Once fermented, it has a wonderful tangy flavor with crunchy texture that complements the salty braised pork.

What are Mustard Greens

Dưa cải, also known as gai choy, Chinese mustard greens and Brassica juncea, have compact heads with thick petioles, large wrapping leaves, and a wonderful mustard flavor. You can find them in the produce section at your local Asian grocery stores.

tray with cut mustard greens, scallions, sliced shallots, and a bowl of salt

Ingredient Notes

Mustard greens: use mustard greens that are firm to the touch. Pick ones that are not too large or small. The smaller ones haven’t had time to develop a nice mustard flavor while the older ones taste too strong. Wash them thoroughly and cut away any brown or rotted parts. Split the mustard greens in half lengthwise then cut them into 1.5-2 inch pieces.
Salt: salt is the key ingredient in vegetable fermentation, deterring pathogenic bacteria while encouraging the good bacteria to work on the vegetables. I like to use unprocessed sea salt for the salt-water brine.
Water: my mom uses a rice water brine for the fermentation process. Rice water is the starchy water that remains after soaking or rinsing uncooked rice. It contains nutrients for the Lactobacilli and helps activate fermentation. If you don’t have rice water, use boiled water instead. She uses the ratio of 1 cup of rice water plus 3 cups of boiled water to 1 tablespoon salt per pound of mustard greens. You want the brine to be salty enough to kill the harmful bacteria but not too salty that it will kill the Lactobacilli.

hand pouring salt rice water brine into jar

What is Lacto-Fermentation

The process for pickling mustard greens is called lacto-fermentation. This simple process requires only vegetables, salt, and water, no sugar, vinegar, canning, or fancy equipment. During lacto-fermentation, the salt used in the brine kills the harmful bacteria but allows healthy bacteria , Lactobacilli, to live. Lactobacilli begin converting lactose and other sugars present in the vegetables into lactic acid which creates an acidic environment that safely preserves the vegetables and gives them a distinctive tangy flavor.

Tips for Pickling

Make sure you clean, rinse, and dry your jars and utensils.
Spread the mustard greens on a large baking sheet and let them dry for 24 hours. You can also leave them near a location with direct sunlight to speed up the process. Drying the vegetables allow them to absorb more of the brine.
The vegetables must be completely submerged under the salted brine to keep an anaerobic environment which prevents oxidation and molding. My mom puts a little ceramic plate over the vegetables and uses a ziplock bag filled with water to weigh everything down and keep the vegetables submerged.

When will the Mustard Greens be Ready

It takes about 3-5 days for the fermentation process. Lactobacilli thrive at 64-75 degrees F. We like to leave the jar of pickled mustard greens on the window sill in direct sunlight for about 4 hours a day. If you leave it in direct sunlight the whole day, the pickled mustard greens will be ready sooner. In the summer, it’s usually ready by day 3 and 4 to 5 in the winter. Check at day three by tasting the mustard green and see if the sourness is to your liking. Once you achieve the desired taste, put it in a cool, dark place in your kitchen or the fridge. We usually finish the pickled mustard greens in a week but you can keep it up to two weeks. They tend to get more sour as time goes on.

For more preserving and pickling inspiration, you might like these recipes: preserved Meyer lemons, pickled cherries, pickled onion and pickled radishes.