The strategy in this easy recipe for pickled red onions is (as one astute reviewer noted) pretty much just “mix everything together and wait.” One more boon for the recipe? It’s entirely made up of pantry staples. The pickling liquid is just a mix of water, salt, sugar, and vinegar—we’ve opted for apple cider, but white wine vinegar, red wine vinegar, sherry vinegar, or rice vinegar would all be fine.
Similarly, you can consider this a blueprint for flavoring these onions however you see fit: Switch out the sweetener for maple syrup or honey, add in ½ tsp crushed black peppercorns, coriander, or red pepper flakes, or toss in a smashed garlic clove or a few sprigs of thyme or oregano. For the prettiest pickles, slice your onions vertically to keep the slivers relatively equal in size.
After letting your quick-pickled red onions sit for at least an hour to soften and marinate, drain them (or store them in their liquid, in the refrigerator for up to two weeks), and then put them to good use brightening up a juicy pile of ribs, sub them into your favorite breakfast sandwich, or scatter them atop a lunchtime grain bowl. They might be simple to make, but these pickled red onions have layers.