Pickled Red Onions

Pre-cooking notes and tips

• Just like in my pickled cabbage recipe, I use a combo of distilled white vinegar and apple cider vinegar to make the brine. You can use either one on its own if you don't have both. If using only white vinegar, though, I'd add another ¼ cup of water to keep the water-to-vinegar ratio at 1:1 since white vinegar has a sharper, more punchy taste.
• Feel free to try other vinegars too, such as white wine vinegar or rice vinegar. See which one you like best. Avoid balsamic.
• I often make these onions just an hour or so before dinner, so I slice them really thin with a mandoline to speed up the pickling. The thinner they are, the faster they pickle. When I'm making them a day or two ahead of use, though, I prefer cutting them by hand into ¼-inch slices. The thicker slices need at least 4 to 6 hours in the brine, but I enjoy them more for their crunch and bite.
• For bigger batches, I usually pull out my food processor (and my husband's swim goggles). It has a slicing blade that works really well for getting through a lot of onions really fast.
• If you're used to soaking sliced onions in water to make them less sharp, you can leave that step out here. The hot vinegar brine does the same job, but better.
• As I mentioned at the beginning, you can change up the spices in this recipe. If you don't want to use whole black peppercorns and coriander seeds, fennel seeds, cumin seeds, bay leaves, allspice berries, and mustard seeds are all good alternatives. You can mix and match, but I'd stick to just two or three different spices (in small quantities) so they don't overpower the onion flavor.
• If you like a little kick, a small amount of crushed red pepper flakes will be a good addition. I sometimes like to throw in a few slices of fresh jalapeño or Thai chilies.
• After the pickled onions have had a little time to rest in the fridge, give them a taste. Add more vinegar if you want extra tang, sugar if you'd like it sweeter, or water if the vinegar tastes too sharp. Make adjustments a little at a time so you don't overdo it. There's no need to heat the liquids. Just add them straight to the jar.
• I usually use regular white sugar, but I've tried honey and maple syrup a few times too. Haven't experimented with any other sweeteners, so I can't say how they'd work.
• Table salt often contains iodine and anti-caking agents. While it works perfectly well for quick-pickling, these additives can sometimes cause the brine to become slightly cloudy after a day or two. That said, I haven't experienced this with the table salt I use. If you'd rather avoid the possibility of cloudy brine altogether, opt for pickling salt, kosher salt, or sea salt.
• I never use the leftover brine to pickle more onions, but I don't throw it out either. I strain it and use it wherever I might normally add a splash of vinegar, like in salad dressings, coleslaw, soups, dips, and marinades.
• Sheesh, almost forgot to mention that while I love red onions for pickling because of their flavor and color, you can absolutely use white or yellow onions too!