Making sauerkraut is similar to making charcuterie—salt and time are the key ingredients. Unlike charcuterie, however, sauerkraut (or any fermented vegetable) is a little more forgiving in the process.
Sauerkraut is simply fermented cabbage with or without spices. Typically, chefs will include caraway seed and juniper berry. The basic flow of making sauerkraut goes something like this: slice the cabbage, add salt, massage to extract as much water as you can, then compress it into a container to submerge in its own juices, weigh it down, and wait.
This is what’s known as dry brine lacto-fermentation. The salt draws out water from the cabbage, which creates a brine that displaces the oxygen around the cabbage to prevent spoilage. The lactobacillus bacteria naturally present on the cabbage thrives in slightly-salty conditions and consumes sugars present in the cabbage, converting them to lactic acid. This raises the pH of the sauerkraut, preserving it and giving it its distinct tanginess.
There are as many ways to achieve this type of fermentation as there are people who make sauerkraut. The amount of salt, or the omission of salt, is highly personal, as are the additional spices. You can also make your own brine instead of extracting liquid from the cabbage or adding water to the cabbage to submerge it. When starting a new batch, some folks also like to add some brine from a previous batch to jump-start the beneficial bacteria. All these are viable options, but a good place to start is with a simple dry brine method to help you fully understand the process and the core concept.
A note before starting: just like with any food prep but especially with fermented foods, you want to make sure you are working with clean tools. This includes your hands and any surfaces the food will contact. You want the naturally occurring bacteria in the vegetable to have a head start. Accidentally introducing harmful bacteria can slow down the process or spoil it.
Step One Making Sauerkraut: Weigh Ingredients Much like baking or making salami, it is best to measure ingredients by weight (grams) instead of volume (cups and teaspoons). Volumetric measurements are inconsistent—kosher salt measures out very differently than sea salt—and they are difficult to scale up or down depending on how much cabbage you’re working with.
First, cut the cabbage then weigh it. I like to use a mandoline to slice the cabbage about ¼-inch thick crosswise. Once you have the weight of the cabbage in grams, you can scale out the salt and spices.
I make most of my vegetable ferments with 2.5% salt by weight. This means for every 1,000 grams of cabbage, I'll be adding 25 grams of salt. This method also makes it easy to scale the recipe to any amount of cabbage (or anything for that matter). If I slice up two heads and end up with 2,135 grams of cabbage, I just multiply that by 0.025 to get the amount of salt I need. In the case of this example, that would be 53 grams of salt (rounded to the nearest full number). Weigh and scale out the spices using the same method.
Step Two Making Sauerkraut: Maceration At this point you have all the ingredients you will be using to make the sauerkraut. Combine them all in a large container and mix thoroughly. You want the salt to make contact with all the cut ends of the cabbage to help draw out the water. After this initial step, I like to let it sit for an hour and let the salt do some of the work before I proceed to the next step.
Now, massage, squeeze, or press the cabbage with your hands or a heavy, blunt object to further press out the water. The goal is to have enough liquid to submerge the cabbage once it is in the vessel it will ferment in. Depending on the time of year and type of cabbage, this can be a breeze or it could feel like trying to squeeze blood out of a rock. Just keep at it slowly, remembering that you don't want cabbage mush. Apply firm pressure but don’t try to kill it.
After this round of cabbage squeezing, I let the cabbage sit for another hour or two to allow the salt to continue drawing water out. Do one final round of massaging and squeezing before packing the cabbage in a container to ferment.
Step Three Making Sauerkraut: Pack It In Now that there’s enough liquid (it won't look like it's enough), you can pack the cabbage and all the liquid into a clean jar, crock, or another non-reactive container. Press down on the cabbage firmly to remove any air pockets. Use a skewer or dull knife to break up any bubbles that form on the sides of the container.
You should have enough liquid to completely submerge the cabbage when you press down on it. And you’re going to need to really press down on it hard and then keep the cabbage submerged so it doesn’t float to the top of the brine. You can use a weight for this-they sell crock weights and other devices online-but you can use pretty much any food-safe heavy object for this if it’s similar in size to the opening of the container. I have used everything from water bottles to small plates and plastic lids to (clean) rocks.
Step Four Making Sauerkraut: Fermentation Place the container somewhere that has a consistent temperature of 65 to 72°F. You have some wiggle room here, but higher temps will speed up the process and lower temps will slow down the process. Try to stay within 10 degrees of the target range.
This process will take two to four weeks depending on the temperature as well as personal preference. The sauerkraut will start developing a tangy flavor after just a few days. At this point, the cabbage will be fairly firm with a lot of crunch still. As time goes on, the cabbage will become softer and the sourness will increase. Taste every few days until you achieve the desired tanginess and texture.
Once the sauerkraut is to your liking, move it into a non-reactive container with a lid and refrigerate. Once refrigerated, the fermentation will slow almost to a stop and will stay that way for a while.
Mold Because the cabbage is submerged in liquid, there should not be any mold growth on the cabbage. But the brine at the top or any cabbage that is out of the brine and exposed to oxygen can form some mold. You can skim and remove this mold from the top of the container and allow the fermentation to continue. Make sure to weigh down any cabbage that wants to float out of the brine.
As the fermentation process acidifies the cabbage and the brine, it’s less likely that mold will form. Pay close attention to the top of the kraut for the first week, removing mold as needed.