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Kiam Chye, Fermented Mustard Greens

Updated: Mar 25

In Chinese cuisine preserved, fermented mustard greens are a key ingredient in a number of dishes. This includes a Singapore Chinese favourite - kiam chya ark tng - salted vegetable duck soup. Fermenting brings a wonderful, tangy flavour to the mustard greens that uplifts dishes. A flavour that commercial store-bought kiam chye, often coloured orange and pickled, simply cannot deliver.

Fermenting is half science and half magic. It is important to enjoy the process without being overly worried about the living culinary creation that will share the sideboard for the next week, perhaps emitting the occasional bubble or belch or two.


The Process

Ideally take 2 days to prepare and start the ferment. It is not complicated, a couple of relatively simple steps to complete. After that the fermenting magic happens over the next week or so.

We suggest using a 2 litre jar for a first attempt. This is a manageable size and creates a decent amount of kiam chye. A 1 litre jar simply doesn’t justify the labour and a larger jar might be over production, for now...


  • A 2-litre jar to ferment in. You can use a Ball or Mason type jar, or, a traditional Chinese fermenting vessel (with a moat style top) if available. If using a larger jar, simply scale up the ingredients. Prior to use, wash and soap the fermenting jar. Rinse it well. Then rinse the jar again with boiling water, taking care not to scald yourself.

A traditional Chinese fermenting vessel
A traditional Chinese fermenting vessel
  • A large jar or receptacle in which to prepare the brine. (enough to hold a litre of water)

  • A kettle, to boil water

  • Chopping board and knife.


  • 1.5kg of mustard greens. Use organic if you like but it is not necessary.

  • Ginger, a thumb sized knob or 2

  • 2 whole garlic cloves

  • 2 red chiles

  • Brine, see below


  • 1 litre of water. Use filtered water or leave out overnight to remove any chlorine.

  • 50g Himalayan or sea salt. Do not use iodised salt.

  • Add 1 tablespoon freshly cooked white rice. Do not use old rice as this can harbour unwanted, harmful bacteria.

  • To make the brine simply boil the water into whatever clean receptacle that you have, and add the salt. Salt dissolves more easily in hot water.


Day 1: Prep Work

To prepare the mustard greens:

  • Rinse the mustard greens in water to remove any debris.

  • Dry the greens, let them drip dry. We prefer leaving the greens to hang in a net bag, to drip dry at our window. The sun can dry them out as well. Not 100% necessary but it adds a little extra to the crunch.

  • Hanging in a window, or balcony, allows the greens to collect some additional airborne yeasts for the ferment. The mustard greens will have their own yeasts already present but doing this can add to the magic of the process.

Day 2: Let's Ferment

Prepare the Brine

  • Create a 5% brine. For every 1 litre of boiled water add 50g of salt. Add the salt while the water is hot, this allows it to dissolve better.

  • Add the rice to the water.

  • Leave to cool (this might take an hour or two)

  • If you need more brine, say, you are making a larger batch of ferment, make sufficient brine for about 75% of the volume of your jar or fermenting vessel.

To make the Ferment

  • Take the mustard greens, trim the stems and cut off any parts that you don’t like.

  • Peel and save one or two of the large outer leaves. Set aside, you will need these for later.

  • Place the garlic, ginger and chiles into the bottom of the clean fermenting jar.

  • Take the mustard greens and squeeze them into the fermenting jar, with stems at bottom, best you can. Pack them in tight and trap the other ingredients underneath. Fit as many as you can, just leave some space at the top.

  • Now take that leaf that you have set aside and see how you can cap the mustard greens under it. This cap will keep the veggies under the brine so that fermentation can take place. You will likely need to trim the edges of the leaf so that it fits into the jar and can hold the greens down. Wiggle it into place.

ferment cap
Placing the 'leaf cap' on the ferment
  • Add the cool brine to cover the greens and cap. If necessary, push down on the cap and adjust its position so that the cap is under the brine and any air is expressed. Add more brine to cover the cap as required.

  • Loosely cover the jar or fermenting vessel top with a lid or cloth. Don’t close tightly with a lid otherwise the pressure from the fermenting gas could explode the jar! If you are lucky to have a traditional Chinese fermenting vessel the ‘water moat top’ neatly solves this problem by allow any gas to escape.

  • Leave the jar in a cool area away from direct sunlight and allow the ferment to begin. After a few hours, or longer, you might see bubbles coming from the vegetables. This is fermentation taking place.



The active, bubbly, phase of the ferment can last a few days. Sometimes there will be more bubbles, sometimes less. Check the jar daily and make sure that the greens remain covered. Add extra brine if you need to. You might see some white yeast growing on the surface, this is fine. If the ferment or surface yeast turns black or smells bad – throw it away. We have never had this happen.

After 3 days of fermenting (not including the preparation days), you might already notice a tangy smell coming from the fermenting jar, a good sign. The color of the mustard greens may have changed slightly. Time for a taste test.

Wash your hands, remove the leaf cap and cut a small piece of the mustard green to taste. You may want to add a little extra salt, perhaps a few teaspoons, if you want. There are no hard and fast rules here, with experience you’ll know how you like it. Replace the cap, add more brine if necessary (just mix some salt and water) and allow to ferment for 7, or perhaps 8 or 9 days. Until you have the taste that you desire. Now you have kiam chye!

fermented kiam chye mustard greens
The finished kiam chye. Note the colour change

The kiam chye is ready for immediate use or store it (in its liquid) in the fridge. The cold will stop the fermentation process. We have kept our kiam chye in the fridge for up to three months but we usually eat it all much sooner. Our favourite use is for duck soup but we also like to use it as a topping for congee or noodles.


Last Thoughts

Every time we make a ferment the results differ. Seemingly linked to the warmth of the kitchen, the mix of the salt and the yeast on the veggies. Don’t be afraid to ferment, it’s well worth it. There is a whole world of fermenting to discover and kiam chye is just the start.

Stay Healthy,

Felicia and Alastair


Check out our other fermenting articles here.

You might enjoy these China fermentation videos by Sandor Kata aka Sandorkraut on YouTube.


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Leeuwendaal NK, Stanton C, O'Toole PW, Beresford TP. Fermented Foods, Health and the Gut Microbiome. Nutrients. 2022 Apr 6;14(7):1527. doi: 10.3390/nu14071527. PMID: 35406140; PMCID: PMC9003261.

Marco ML, Sanders ME, Gänzle M, Arrieta MC, Cotter PD, De Vuyst L, Hill C, Holzapfel W, Lebeer S, Merenstein D, Reid G, Wolfe BE, Hutkins R. The International Scientific Association for Probiotics and Prebiotics (ISAPP) consensus statement on fermented foods. Nat Rev Gastroenterol Hepatol. 2021 Mar;18(3):196-208. doi: 10.1038/s41575-020-00390-5. Epub 2021 Jan 4. PMID: 33398112; PMCID: PMC7925329.



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