01 -
Start by peeling your red onion and slicing it into thin rings. You can go for thinner slices (around ⅛ inch) if you want them to pickle quickly and be easier to pile on sandwiches, or slightly thicker (up to ½ inch) if you prefer more crunch. I find that a sharp knife works great, but a mandoline is perfect if you have one. Place all your beautiful onion slices into a clean jar that has a tight-fitting lid – a pint-sized mason jar usually works perfectly. If you're using the optional beet for color, add a small peeled piece to the jar as well.
02 -
Grab a small saucepan and add the water. Bring it to a boil over medium heat. Once it's bubbling, add the sugar and salt, stirring until they completely dissolve. Then pour in both the apple cider vinegar and the white vinegar. The combination of the two gives a perfect balance of flavor! Bring this mixture to a gentle simmer – you don't want a rolling boil, just enough heat to ensure everything is well combined.
03 -
Once your liquid is simmering, add the peppercorns if you're using them. Give everything a quick stir, then remove the pan from the heat. Let the pickling liquid cool for just about 2 minutes – you want it still quite warm but not boiling hot when you pour it over the onions.
04 -
Place your jar of sliced onions in the sink or on a plate (to catch any potential overflow). Carefully pour the warm pickling liquid over the onions, making sure to include all those tasty peppercorns. Using a spoon or fork, gently press the onions down to make sure they're completely submerged in the liquid. If some pieces try to float up, that's normal – just push them down a few times and they'll eventually stay put.
05 -
Put the lid on your jar and let the onions sit at room temperature for at least 30 minutes, or up to an hour if you have the time. You'll actually be able to see them change color before your eyes, turning that gorgeous pink-purple shade as they pickle. The onions will soften slightly but still maintain a nice crisp texture. After 30 minutes, they're ready to enjoy, but the flavor gets even better if you can wait a bit longer!
06 -
Once your onions have pickled at room temperature, you can serve them right away or refrigerate them for later use. They'll keep beautifully in the refrigerator for 1-2 weeks, and the flavor actually continues to develop over the first few days. Use them to top your tacos, sandwiches, salads, burgers, grain bowls, avocado toast – pretty much anything that could use a bright pop of flavor and color!