Stir together the water, vinegar, sugar, & salt in a pan.
Cover and bring to a boil.
Turn down heat and simmer for 3 minutes or until the sugar and salt crystals are dissolved.
Let cool about 10 minutes.
Pack the onion slices down in a jar.
Add the garlic clove and the peppercorns.
Pour the cooled pickling liquid over the top.
Cover tightly.
Shake a little to mix things up and refrigerate 30 minutes before using.
Notes
Storage:Make a big batch of these easy pickled onions because they last for up to two weeks refrigerated in an airtight container (like the mason jar!) This quick pickled onion recipe was formulated as just that—a "quick" pickle. For that reason, I don't recommend canning or saving these pickles any longer than two weeks.Tips:
For the pickling mixture to fully soak into the onions, use a very sharp knife to create thin, even slices.
Panera pickled red onions will lighten in color when they're fully pickled, and turn from a purple shade to pretty pink.
If you prefer thicker slices of onions, that's fine. However, they will take longer to pickle. In this case, consider prepping the pickled onions earlier in the day or even a day prior to serving.
A little sugar helps balance the flavors but you can leave it out if you want.
When the onions are gone you can reuse the vinegar mixture for a new batch.