My favorite way to preserve vegetables is through fermentation. This means a lot of sauerkrauts and variations on krauts, as well as a few brine pickles, relishes, and chutneys. Fermenting is a huge topic that covers a lot of kinds of food preservation and is backed by deep traditions and science, so while I’ll share a basic recipe here I highly recommend getting some books on the subject. There are many excellent titles out there, but my go-to in the kitchen is Fermented Vegetables by Christopher and Kirsten Shockey. This is my favorite because it is accessible and basic enough to grab mid-recipe and clarify something, but it has enough background information and research to be something you can pour over for hours.
A basic ferment, in this case a sauerkraut, starts with your garden fresh vegetable. Many, many vegetables can be fermented. There are a few that won’t work, but you’d be surprised what will. This year in my kitchen we fermented cabbage, carrots, onions (into a relish), beans (in a pickling brine), and eggplant. Of course, cabbage is the go-to for sauerkraut. Red cabbage can work just as well for sauerkraut, and nappa cabbage is a staple for kimchi.
After you harvest your cabbage, wash it off and remove the tough outer leaves. The cabbage will have to have the thick root stem removed, and the remaining tender inner leaves chopped roughly.
All of this goes into a large bowl. You can do mixed krauts, or add a flavoring herb at this point. I’ve mixed carrots and onions with the cabbage, and added garlic, curry, red pepper flakes, and ginger depending on the taste I’m going for. You don’t want to overwhelm the flavors, so I would consult a recipe and taste your sauerkraut regularly as you mix it. It’s probably best to start with a ‘naked kraut’ - that is, just salt and cabbage.
Next, you will add salt to your chopped cabbage. This is the key of fermenting a sauerkraut. With things like carrots or beans being preserved through a pickling brine, the process is similar but this step is achieved by pouring a prepared brine over the vegetables. But in the case of krauts, the vegetables make their own brine.
A tablespoon of salt to a head of cabbage is a very general rule. Start small, and taste regularly. You can always add more salt, but you can’t take it out!
Massage the salt into the cabbage. You can use a wooden tamper for this if you wish, or just use your (clean) hands. You will want to keep working, firmly massaging, until the leaves of the cabbage start to become more limp and release a juice that will start to pool in the bottom of the bowl.
If you aren’t getting enough brine out of your cabbage, you can try letting it sit for an hour or so and then massage it again. You can also add a squeeze of lemon or lime to bring out the acidity and add some liquid, or you can throw in a tablespoon of brine or pickling juice from a previous ferment.
Once you’ve generated the brine you can pack your ferment into prepared fermenting vessels. If you’re doing a large batch you might use a crock designed for this purpose, but I use mason jars. As you add the vegetables to the jar, tamp them down so they’re all squished in. You want to keep the brine level above the vegetables so try to tamp them down far enough that they’re submerged.
Leave space in the jar for some expansion and for a follower weight. This weight helps keep your ferment below the brine during the fermentation process. There are specifically designed glass weights which work wonderfully, or you can put a little bit of water in a ziplock bag and use that to tamp the ferment down. Just make sure the bag is carefully sealed!
Once your ferment is jarred, weighted, and below the brine, it is time to leave it to do its thing. Most fermenting recipes take a week to two weeks. They should be stored in a cool (55-75F) place out of direct light. After a week you can start tasting your ferment, and you can decide when it is the taste that you desire.
During the fermentation process you’ll want to burp your jars daily if you’re using regular mason jar lids. You can also use airlock tops on the jars during the fermenting process. You should see bubbles moving around inside the jars and quite a bit of action any time you burp the jar.
There isn’t a magic way to know your ferment is done, the best way to tell is just by tasting. It should taste fresh and sour but not to acid-y. The vegetables in the ferment should be firm, not slimy. If you have slimy vegetables or a bad smell, the ferment is off and should be discarded.
A finished ferment can be put in a clean mason jar with a traditional lid, sealed, and stored in the refrigerator. Ferments can stay good for a year or more - but they don’t usually last that long in our house!