Place your sliced (or diced) onion in a quart canning jar.
Combine all of the rest of the ingredients in a sauce pan to create a brine and bring it to a boil over medium heat. Once it boils, removed it from the heat.
Pour the brine into the jar with the onions. Use a spoon or other utensil to press the onions down into the liquid. Allow this to cool to room temperature.
Close the jar and refrigerate 24 hours.
Enjoy!
Video
Notes
Your pickled onions will stay good for about 2 weeks in your refrigerator.