Instructions

1. Slice onions as thin as possible and place in a shallow bowl or quart-sized mason jar. Set aside. 
2. In a measuring cup, combine warm water, apple cider vinegar, sugar, salt, and peppercorns (if using). Stir until salt and sugar dissolve.
3. Pour liquid over sliced onions and stir to combine. Press onions down so that they’re completely covered with liquid. 
4. Cover bowl with a clean towel or loosely place lid on jar. Allow onions to rest on the counter at room temperature for 1 hour before serving or transferring to the fridge for longer storage. Will keep in the fridge in a tightly covered container for up to 3 weeks (jars like this are ideal for storing and serving from) and will intensify in flavor and color. 

Note: This is a refrigerator-type pickle and not intended for canning.