I love red onions because even just a few slivers of fresh red onion can truly transform a recipe (see Thai Curry Vegetable Soup and Slow Cooker Coconut Curry Lentils) and there’s no substitution that is really quite like it. BUT I can rarely find a red onion that is smaller than a softball and I usually only need 1/4 or less of it for a recipe. Because I hate to waste the rest of the onions, I always use the leftovers to make a batch of these Pickled Red Onions

Overhead view of a bowl of pickled red onions on a wooden plate with wooden bowls on the side

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What Are “Quick” Pickles?

There are two methods for pickling vegetables: through fermentation or by using a vinegar-based brine. Both methods use a salty and acidic liquid to prohibit the growth of dangerous bacteria. With fermentation, the acid is created by microorganisms, but this can take days or even weeks to accomplish. Store-bought vinegar creates this brine almost instantly, hence the name quick pickle.

The trade-off for this quick process is that quick pickles do not contain probiotics, like fermented pickles, and the flavor can be a little more one-dimensional. Fermented pickles are a bit more of an exact science and can take some practice to get right (here’s a recipe for Fermented Sour Pickles, if you’re interested), whereas quick pickles are pretty hard to mess up.

How to Use Pickled Red Onions

Pickled red onions are AWESOME on tacos, sandwiches, carnitas, salads, pizza, nachos, flatbread, avocado toast, burgers, and lots of other things (practically any Mexican dish). Instead of thinking of these pickled red onions as a substitute for fresh red onions, think of them as a non-spicy alternative to pickled jalapeño. That tangy pickled flavor tastes great anywhere you’d normally use a pickled jalapeño.

How long do They Last?

Keep your pickled red onions refrigerated and in the brine and they’ll last 3-4 weeks in the refrigerator! The flavor gets better over time as the onions marinate in the brine. Just make sure to keep your pickled red onions refrigerated in a non-reactive, air-tight container, like a mason jar or other food-safe storage container.

Customize Your Onions

There are a million different ways to make pickled red onions, so I’ve provided a very basic version below. As you begin to make them more often, you can start to tweak the flavors to match your preferences. Experiment with the seasonings and spices by adding ingredients like bay leaf, star anise, sliced jalapeño, or red pepper flakes.

What Kind of Vinegar to Use for Pickled Red Onions

The recipe below uses white vinegar, but you can use different kinds of vinegar in your pickled red onion recipe to change the flavor. I suggest not using vinegar with strong flavors so they don’t overpower the onions or the other ingredients. Try using rice vinegar, white wine vinegar, red wine vinegar, or apple cider vinegar in your pickled red onions!

(Tacos made with Chili Rubbed Pulled Pork, fresh jalapeño, pickled red onion, and cotija.)

Pickled Red Onions

4.81 from 73 votes

Pickled Red Onions are a great way to use leftover red onion and are a great topping for tacos, sandwiches, pizza, and more.

Author: Beth Moncel

Side view of a bowl of pickled red onions on a wooden plate

Servings 10 1.5 cups total

Prep 10

Cook 5

Soak Time 30

Total 45

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Ingredients

1.5 cups sliced red onion ($0.32)
1 clove garlic ($0.08)
3 Tbsp white sugar ($0.06)
1.5 Tbsp salt ($0.15)
1/2 tsp peppercorns ($0.05)
1 cup white vinegar ($0.06)

Instructions

Thinly slice the red onion into 1/8-inch slices. Peel the garlic. Place the onion and garlic in a large glass or ceramic bowl.
Add the sugar, salt, and peppercorns to a small sauce pot. Add the vinegar and stir until the sugar and salt are dissolved. Place a lid on the pot and bring the mixture up to a boil over medium-high heat.
When it reaches a boil, pour the vinegar over the sliced onion and garlic.* Press the onion down so all the pieces are submerged, then let the mixture cool to room temperature. I sometimes place a piece of plastic wrap over the onions to help push and hold them below the surface of the brine (see step by step photos below).
Once cool, use the onions immediately or transfer the onions and all the brine to a covered non-reactive container (glass, ceramic, or plastic) for storage in the refrigerator. The onions can be stored in the refrigerator for 3-4 weeks.

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Notes

*For onions that remain crunchy, pour the boiling vinegar over the onions in the bowl. If you prefer soft onions, add the onion and garlic to the sauce pot and allow them to boil in the vinegar for 1-2 minutes before transferring to a non-metal bowl to cool.

Nutrition

Serving: 1recipeCalories: 214.6kcalCarbohydrates: 53.4gProtein: 2.1gFat: 0.3gSodium: 3547.8mgFiber: 3.5g

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How to Make Pickled Red Onions – Step by Step Photos

Sliced Red Onion on a green cutting board

This recipe works for up to about 2 cups of sliced red onion, but you can use less if you have less. It’s great for using up a leftover half onion, but I’ve used a whole onion for demonstration purposes here. Slice the onion into ⅛-inch slices.

Place the sliced onions and one clove of peeled garlic in a large ceramic or glass bowl.

Salt, sugar, and peppercorns in a saucepot, vinegar being poured over top

Add 1.5 Tbsp salt, 3 Tbsp sugar, ½ tsp whole peppercorns, and 1 cup white vinegar to a saucepot. Stir to dissolve as much of the salt and sugar as possible. Place a lid on the pot and bring it up to a boil over medium-high heat.

Vinegar in a bowl with sliced onions, plastic wrap on top

Carefully pour the boiling vinegar brine over the sliced onions and garlic in the bowl. Stir to combine and press the onions below the brine. Allow the mixture to come to room temperature. I like to take a piece of plastic wrap and press it down onto the onions to help them stay below the brine just as soon as it’s cool enough to touch.

As the onions soak in the brine they’ll begin to turn an incredibly vibrant shade of pink. The pigment in red onions and red cabbage is a natural pH indicator. Don’t you just love food science??

Overhead view of pickled red onions in a bowl on a wooden plate next to bowls of peppercorns and salt.

Once the onions have come to room temperature and are a vibrant pink color, transfer them to an air-tight food storage container and refrigerate until ready to eat, or up to 4 weeks. The flavor gets even better after a few days!

Three pulled pork tacos with pickled red onions and jalapeños.