Pickled Red Onions are a great way to use leftover red onion and are a great topping for tacos, sandwiches, pizza, and more.
Thinly slice the red onion and peel the garlic. Place the onion and garlic in a large glass or ceramic bowl.
Add the sugar, salt, and peppercorns to a small sauce pot. Add the vinegar and stir until the sugar and salt are dissolved. Place a lid on the pot and bring the mixture up to a boil over medium-high heat.Once boiling, pour the vinegar over the sliced onion and garlic*. Press the onion down so all the pieces are submerged, then let the mixture cool to room temperature.
Once cool, use the onions immediately or transfer the onions and all the brine to a lidded non-reactive container (glass, ceramic, or plastic) for storage in the refrigerator. The onions can be stored in the refrigerator for 3-4 weeks.
*For onions that remain crunchy, pour the boiling vinegar over the onions in the bowl. If you prefer soft onions, add the onion and garlic to the sauce pot and allow them to boil in the vinegar for 1-2 minutes before transferring to a non-metal bowl to cool.