If you’ve read my blogs before, you know that preserves are a big part of my repertoire. I love pickles, fermentations, cures, brines, dehydration, you name it. I usually write about the more obscure side of that world, but today I want to share something simple, accessible, and delicious: pickled red onions.

A lot of people make pickled red onions that taste great, but let’s be honest: they don’t always look great. Instead of that vibrant fuchsia-pink that makes dishes pop, they come out dull, grayish, or worse, a muddy purple. So let’s break down the process of making onions that are as beautiful as they are tasty.

Pickled red onions

Start with the Right Onion

Not all red onions are created equal. Size and age make a big difference in the final color. Once, I pickled 30 pounds of baby red onions, about the size of clementines, and the result was nearly black. Luckily, it was Halloween. For that iconic hot-pink hue, I go for larger onions, tennis ball size or bigger. They tend to have a more balanced pigment-to-sugar ratio, and they give me that punchy fuchsia tone I'm after.

And yes, slice with the grain. It holds texture better and just looks sharper in the jar.

Sliced red onions

Vinegar: Don’t Overthink It

A lot of chefs joke that white distilled vinegar is only good for washing your socks. And to be honest, I usually agree. But when it comes to quick pickling, it’s a powerhouse. It’s pure diluted (yeah, I know,contradiction) acetic acid, which means it doesn’t bring much flavor of its own. That’s a good thing. The sharpness lifts the natural flavor of the vegetable, rather than covering it up.

I use all kinds of vinegars in other pickles (sherry, champagne, rice) but for red onions, I keep it dead simple.

The Pickling Liquid (My Go-To Ratio)

This is a solid, balanced base you can scale up or down depending on your needs. It works for just about any quick pickle:

1 cup white distilled vinegar
1 cup water
2 tablespoons sugar
2 teaspoons kosher salt
(Optional) A pinch of chili flake, for a gentle kick

That’s it. The chili flake adds just a bit of heat in the background. Not enough to make it spicy, but just enough to make it interesting. You can leave it out if you prefer a cleaner flavor, or dial it up if you're a fan of heat.

You can double the vinegar if you like a sharper bite. I won’t judge. Food is personal. Experiment, adjust, and find what works for you. But this is the ratio I come back to again and again.

Store it in your fridge and use it hot for onions, or cold for cucumbers, radishes, or whatever else you’re pickling that day.

Temperature: The Secret to Color

Here’s the part most people miss: the temperature of your pickling liquid is critical to getting that bold color.

If the liquid is too cool when you pour it, your onions will come out dingy, gray, or pale. Not good. Right before pouring, your liquid should be at a rolling boil. That heat gently cooks the onions on contact, which softens the texture just a touch and activates the pigments.

Red onions get their color from compounds called anthocyanins. They’re sensitive to both heat and acidity. The hot, acidic liquid creates the perfect conditions for that vibrant transformation.

After pouring, let your onions cool at room temperature. Don’t rush them into the fridge. Cooling too quickly can dull the color and mess with the texture.

Pickled red onions

How to Make One 16 oz Jar of Pickled Red Onions

You’ll need:

1 large red onion, sliced with the grain
1 batch of the pickling liquid (recipe above)
1 16 oz mason jar or any sealable container

1. Pack the sliced onion into the jar or container.

2. Bring the pickling liquid to a rolling boil.

3. Carefully pour the hot liquid over the onions, fully submerging them.

4. Immediately screw the lid on.

Yes, the lid might seal as the jar cools.
No, this is not proper canning.
Regardless of whether the button pops, refrigerate the jar once it reaches room temperature.

5. (Optional) Add a pinch of chili flake to the jar before pouring in the liquid.

6. Using a larger container? Press a piece of plastic wrap directly over the surface of the onions to keep them submerged. Don’t seal the edges, just let it float.

7. Let the jar cool to room temperature on the counter. Once cool, store it in the refrigerator.

Ideally, let the onions sit overnight before using them. They’ll keep for several weeks in the fridge - if they last that long.

These are my go-to pickled onions, and I have been using this method most of my career. Whether you’re topping tacos, grilled meats, sandwiches, grain bowls, or a salad, they bring a burst of acid and color that transforms a dish.

Pickled onions on salad Once you’ve got this method down, you’ll never be without a jar in your fridge. And if you mess around with spices, vinegar blends, or different vegetables, please comment below! I love hearing about your experiments. Happy pickling!