I’ve harvested all of the spring planted kohlrabi now. It did pretty well, all things considered, and I got a little over 20 pounds of it. Since my wife and I both like it, I generally plant quite a bit in both spring and fall. We love eating it raw and cooked, but one of my new favorite things to do with it involves lacto-fermentation.
I’ve done it two different ways. One way is to make kohlrabi pickles. You can cut them in any shape you choose, but I usually peel the kohlrabi and then cut into spears or slices. For this treatment you need to make a 5% brine solution. I add 1.5 tbsp/22g of sea salt to 2 cups/450g of water and stir until the salt is dissolved. Next I pack the kohlrabi pieces in a clean wide-mouth glass jar, then pour in the brine solution to cover. I also like to add a few cloves of crushed garlic and maybe a dried hot pepper. But truthfully the fermented kohlrabi is pretty tasty on its own. Pickling spices, dill or mustard seeds would also add a nice flavor.
I put a leaf from the kohlrabi (or a piece of cabbage leaf) in the top of the jar to help keep the pieces submerged in the brine. Then I cover loosely with a ring and lid, and place the jar on a saucer or bowl. Once the kohlrabi starts fermenting, the brine tends to bubble out and the saucer will help keep it from running all over the place. And be sure to leave the lid loose so the jar doesn’t explode from the carbon dioxide gas produced by fermentation. I leave the jar sitting at room temperature to ferment, and taste the kohlrabi after a few days to see if it’s ready. Once it’s tangy enough for my tastes, I put the jar in the refrigerator. The kohlrabi pickles make a great snack, and a tasty way to get some probiotics.
The other way I do it is to make kohlrabi kraut. I make it much like I would cabbage kraut, except I use kohlrabi. First I peel the kohlrabi, then shred using a grater. I’ve used both a medium and a coarse grater with good results. It takes about two pounds of raw kohlrabi (before peeling) to make enough to fill a quart jar. After peeling and shredding I usually wind up with about 1.75 pounds/800g of kohlrabi.
Next I put the shreds in a mixing bowl and add 1 tbsp/16g of fine sea salt, which is 2% of the weight of the kohlrabi. I work the salt in with my hands, kneading and squeezing until it is well combined and the kohlrabi is starting to release its juices. You can also use a potato masher or a wooden pounder. Then I pack the kohlrabi and all the juice into a clean quart jar, add a leaf and then cover loosely with the ring and lid. I leave it to sit at room temperature too, and I find it is usually tart enough for my tastes in less than a week. Then it’s off to the refrigerator, where it will keep for a long time as it continues to slowly improve in taste.
You can use the kohlrabi kraut the same as you would regular sauerkraut. My favorite use is to make a meatless Reuben sandwich. That combines some of our homemade kraut, sliced cheese and rye bread. Sometimes I fix this in a skillet, other times I put it on the grill and cook just long enough to melt the cheese and char the bread a bit.
Some fermenting recipes call for adding dairy whey to provide a starter culture of beneficial bacteria, and I’ve done this in the past. However, I’ve found that my kohlrabi generally ferments just fine without the added whey. Some people also add a bit of the juice from a previous batch of sauerkraut or other fermented vegetables and use that as a starter, but again, it really isn’t necessary. The kohlrabi will ferment just fine without anything added as a starter.
If you are new to lacto-fermentation, I can recommend a couple of books I use for reference on the subject. One is The Art of Fermentation by Sandor Katz. The author is a self-described “fermentation revivalist” and the book is a thorough guide to all kinds of home fermentation. The other book is The Complete Idiot’s Guide to Fermenting Foods by Wardeh Harmon. This one has a lot of recipes and is a good starting point for those interested in making their own fermented foods. Both address the food safety issues involved in home fermentation, and will help to make sure your homemade fermentation projects are successful.