How To Pickle Onions

Pickled onions can feel like a cook's little secret, says food blogger & photographer Ksenia Prints of At the Immigrant's Table. Their beautiful pink color can instantly bring a smile to one's face and bright contrast to the plate. Their sharp, acidic flavor also helps to lift a dish up, adding a pleasant burst of lip-puckering acidity to anything it touches. 

Moreover, their soft texture feels like the result of hours upon hours of work. But is that really the case? Just how long do onions really need to pickle? And what's the secret to getting that lovely pink color just right?

Read on to discover how to pickle onions quickly, easily, and deliciously. And, no, it's not going to take you hours of hands-on work. Once you learn this easy recipe for some seriously tasty pickled onions, there will be no going back!

The first step to pickling onions is cutting them right. First, peel the papery skins off your red onions. Then, cut an onion in half, going vertically from the root to the top.

With the onion laying face down on a cutting board, make lengthwise cuts along the onion, going from one side to the next. The resulting slivers of onion should be very thin — no more than ¼ of an inch thick. Take your time and make the thinnest cuts possible, using as sharp a knife as possible. Thinner slices of onion will pickle more easily and quickly than thick ones, so there's no need to rush here. If you want to scale this recipe up for a larger batch, simply repeat this process with all of your red onions.

Now, with a pile of onion slices at your fingertips, it's time to make the all-important marinade for pickled onions. In a medium-sized bowl or a 16-ounce (500-milliliter) jar, mix the apple cider vinegar with salt and sugar. If you want to get a little fancy or play around with some additional flavorings, you can add fresh sprigs of thyme or rosemary, whole cumin, or even coriander seeds. 

None of that is strictly necessary to make great pickled onions, of course, but these flavors can add an extra dimension if you're looking to try something a little different. The really important players here are in the trifecta of vinegar, salt, and sugar. These three simple ingredients will lend flavor and also kick-start the all-important pickling process.

The best vinegar for making pickled onions is apple cider vinegar. White vinegar can be a bit too strong, with its abrasive nature. To be fair, white vinegar is great for making pickles that are meant to be canned and kept in the cupboard, but it's too much for the delicate dish that is quick-pickled onions. Other kinds of vinegar, like rice vinegar, balsamic, or red wine vinegar, all have additional notes of flavor that hide the natural sweetness of the onion.

Compared to all the other vinegars out there, apple cider vinegar has the perfect balance of sweetness and acidity that will have you singing with joy once you taste your pickled onions.

Normally, to make a quick pickling marinade, vinegar is boiled with salt, sugar, and spices to produce a fast-acting pickling solution. If you're a little sensitive to the smell of vinegar, heating it up can admittedly make the scent all the stronger in your kitchen. But not in this case!

Onions, especially if thinly sliced as you've already done here, are fairly delicate and can take up all that pickling liquid without heat (and, in fact, heating may overpower the crunchy texture of those onions anyway). Moreover, the relatively sweet apple cider vinegar is just acidic enough to do the job all on its own in the refrigerator. All of this is to say that your stove can stay off and your pots and pans remain safely in the cabinet for the duration of this recipe!

Pickled onions turn pink because the color slowly leaches out of the purple onions. This is the action of the vinegar as it works its way into the onion, letting the bright purple from the outer layers bleed into the solution.

You may have already guessed this, but, if you make your pickled onions with white onions, they will not be as colorful. They should still taste great but know that you'll then be getting your only color from the reddish-brown apple cider vinegar. For the full effect, we recommend using red onions.

Once you've mixed up your apple cider vinegar, sugar, and salt, all you need to do is to add the thinly sliced onion to the marinade. Stir the mixture well to ensure onions are submerged under the liquid. If you need to add more marinade to cover the onions completely, feel free to do so. Eventually, the onions will begin to soften and break down a bit, releasing their own liquids and further sinking into the marinade mixture.

Now, we must admit that this part requires a bit of patience, though the hands-on portion of your onion pickling process is pretty much over at this point. So, with the onion slices sitting pretty in their marinade, simply let them sit in the liquid for at least 10 minutes. Ideally, however, you'll let them go even longer.

These work pretty well after an hour of pickling, but we love pickled onions best after one night in the refrigerator. After that amount of time, they are soft like delicate strands of silk, curling in on themselves when you add them to salads, sandwiches, or taco bowls. The more time you can give them, the more you'll get that lovely pink color, too!

All told, pickled onions will last in a sealed jar in the refrigerator for months. Keep them on the condiment shelves with the sauces, or on the top shelf of the fridge. They're great added to tacos, burgers, salads, and perhaps snagged as a quick snack here and there, too.

The longer pickled onions sit, the stronger the pickling flavor will be. This process will also further soften the onion strands and infuse everything with flavor. And, if you need some encouragement, popular TV chef Bobby Flay is a huge fan of pickled red onions, too. So, chances are good that you'll want to keep a jar of this sweet and sour onion mix in your fridge at all times, too!