Recipe: Fermented Red Onions

Pickled onions are one of our favorite condiments and we always have a jar of homemade ones on hand. For this fermented onion recipe, we used red onions because their sweetness, paired with the natural sourness of lacto-fermentation, makes this a deliciously tangy fermented snack that’s packed full of umami.

Here at FarmSteady, we love our fermented vegetable recipes. Why? Because they are some of the easiest and tastiest ferments you will ever make, and they are perfect if you are a beginner just starting to get your fermentation groove on. Give this fermented red onion recipe a go (our Fermented Vegetable Kit makes it super easy), and soon you will start using pickled onions on everything from burgers to tacos, and even to spice up your avocado toast.

Fermented red onions are closer in texture to cooked onions than raw. The process of fermentation breaks down the onion’s crisp texture, transforming them to a smooth and silky condiment. If you usually avoid raw onions because of their bite and pungent flavor, pickled onions are a great alternative. In addition to the change in taste and texture, the fermentation process makes onions easier to digest and even more nutritionally beneficial than if you were to cook them. Lacto-fermentation creates a ferment packed with natural probiotic cultures that our gut loves, so this is not just a delicious condiment, but a healthy one too. This is why we prefer homemade to store bought, as pickled onions from the store are not always fermented.

How to ferment red onions

For this fermented red onion recipe, you will only need three ingredients: red onions, salt, and water. If your onions are relatively large in size, you can use three of them, otherwise you may need four medium-sized ones.

First, we need to prepare the onions by cutting off the woody ends and peeling them. Next, you can cut your onions in half and start to thinly slice them. We want nice silky onion strings for the end-product, so no dicing required.

Transfer your sliced red onions to a big bowl and sprinkle them with 1.5 tablespoons of Kosher salt. The next step is the fun part–massage your onions. Start working the salt into the onions by pressing and massaging them with your hands. This will cause the onions to start sweating as they release their juices. You will feel the onions break down and soften as you massage them. Once they don’t feel crispy anymore, transfer them to your fermentation jar and use your fermentation weight to weigh them down. Next, add half of a cup of water and close your jar and airlock. You will have to check the water level in the jar the next day and top it off so the onions are fully submerged when weighted.

The fermentation process takes 5-7 days, depending on how they taste and your preference. Keep your onions at room temperature and taste your ferment around day 5. You can measure the amount of tang and depth of flavor according to your own taste buds. Once you have decided your ferment tastes absolutely delicious, you can store it in the fridge where it should last for at least two months–that is if you can stop yourself from not eating it all within the first few days.