Step 1: Slice the Onion
Peel the red onion and slice it thinly into rings or half-moons. How thin? About ⅛ inch is perfect—thin enough to pickle quickly, thick enough to keep some crunch. Place the sliced onions in a clean 16-ounce glass jar.
Step 2: Make the Pickling Liquid
In a small saucepan, combine the apple cider vinegar, water, sugar, and salt. Stir everything together and place over medium heat. Heat just until the sugar and salt dissolve—you'll see the liquid go from cloudy to clear. Do not let it boil.
Step 3: Add Your Spices (If Using)
If you're adding any of the optional ingredients, drop them into the jar with the onions now.
Step 4: Pour and Submerge
Carefully pour the hot vinegar mixture over the onions in the jar. Make sure all the onions are completely submerged. If they're floating, you can press them down with a spoon or add a little extra water to cover.
Step 5: Cool and Refrigerate
Let the jar sit uncovered until it cools to room temperature. Then screw on the lid and pop it in the fridge.
Step 6: Wait (If You Can)
The onions are technically ready in about an hour—they'll be lightly pickled and delicious. But if you can wait a few hours or overnight, the flavor deepens and they become something truly special.
Tips for Perfect Pickled Onions
Slice evenly. Uniform slices mean consistent pickling. A mandoline makes quick work of this, but a sharp knife and steady hand work just fine.
Pack the jar loosely. You want the vinegar mixture to flow freely around all the onions. Overstuffing can lead to uneven pickling.
Don't skip the salt. It's not just for flavor—it helps preserve the onions and keeps them crisp.
Use a non-reactive container. Glass is perfect. Avoid metal bowls or containers, which can react with the vinegar.
Keep them submerged. If onions peek above the liquid, they can discolor or spoil. Weigh them down with a smaller jar or add a little extra vinegar-water mixture if needed.
Ways to Use Pickled Red Onions
On tacos—any kind, but especially carnitas, fish, or black bean
Piled onto sandwiches, burgers, or hot dogs
Tossed into salads or grain bowls
On top of avocado toast
Alongside eggs—scrambled, fried, or in a breakfast burrito
On a cheese or charcuterie board
In rice bowls or buddha bowls
On grilled meats or fish
Stirred into tuna or chicken salad for crunch and tang
Variations to Try
Spicier: Add a full teaspoon of red pepper flakes or a sliced jalapeño to the jar
Herby: Tuck in a few sprigs of fresh dill, thyme, or oregano
Mexican-style: Add a pinch of dried oregano and a slice of jalapeño
Garlic-lover's: Use 2-3 smashed garlic cloves instead of one
Lime twist: Substitute half the water with fresh lime juice for extra brightness
Honey-sweetened: Replace the sugar with 1 tablespoon honey (stir until dissolved)
Storage
Refrigerator: Store in an airtight jar for up to 2 weeks. The flavor will continue to develop over the first few days.
Note: These are refrigerator pickles, not shelf-stable. Always keep them cold.
Recipe Summary
Prep time: 10 minutes
Cook time: 5 minutes
Total time: 1 hour 15 minutes (includes minimum marinating)
Servings: About 8 (2 tablespoons per serving)
Approximate calories: 15 per serving
