Thinly slice 1 large red onion and place in an appropriately sized mason jar or delitainer.
1 large red onion
Sprinkle liberally with kosher salt, cover and shake. Let rest while you assemble other ingredients.
kosher salt
Add in black peppercorn, allspice berries, dried chili, garlic, bay leaves, ½ teaspoon granulated sugar
1 Tbsp black peppercorns, 5 allspice berries, 1 small red chili, 3-4 cloves garlic, 1-2 bay leaves, ½ tsp granulated sugar
Cover onion slices with rice wine vinegar (apple cider vinegar works here too, as will plain white vinegar, but to make up for some of the sweetness add in an extra ½ teaspoon of sugar if you do)
rice wine vinegar
Cover, shake a few times to disperse the flavorings and pop in your fridge.
Notes
Expert Tips
Slice with the grain, not against it. Cutting your onions vertically (root to tip) rather than into horizontal onion rings gives you a better bite and helps them hold their shape and crunch in the brine instead of going limp.
Don't skip the salt step. Salting and letting the onions sweat for a few minutes before adding vinegar softens their sharp bite and helps them absorb the brine more evenly.
Warm vinegar = faster pickles. If you're short on time, gently warm your vinegar (don't boil) before pouring it over the onions—this speeds up the pickling process so you can enjoy them in under an hour instead of waiting the full two.
Let them rest for maximum flavor. While these quick-pickled onions are technically ready in 2 hours, the flavor keeps improving overnight and beyond—if you can plan ahead, you won't regret the wait.
Use a non-reactive container. Stick with glass jars or food-safe plastic instead of metal bowls or containers, since the acidic vinegar can react with certain metals and affect flavor.
Keep the vinegar solution. Don't toss it once the onions are gone! Strained pickling liquid makes a fantastic instant vinaigrette base or a quick flavor boost for marinades.
Adjust acidity to taste. If your pickles taste too sharp after chilling, stir in an extra pinch of sugar; if they're too sweet, a small splash of extra vinegar will balance things back out.
Storage Instructions
Fridge: Store your pickled red onions in an airtight container or mason jar in the refrigerator, where they'll keep well for up to 2 weeks. Make sure they're fully submerged in the brine to maintain the best flavor and texture.
Make-ahead friendly: These are perfect for meal prep. Make a batch (or two!) at the start of the week and add them to whatever you're eating all week long.
Freezing: Not recommended. Freezing breaks down the onion's texture, leaving you with mushy, waterlogged pickles once thawed—so stick to the fridge for these.
Signs they've gone bad: Toss the batch if you notice a cloudy or slimy brine, an off or unpleasant smell, or any mold. Properly made and stored, though, they should stay fresh and crisp for the full 2 weeks.
Double batch it: Since they keep so well and get used up fast once you start adding them to everything, don't be afraid to double the recipe right from the start.