Line a rimmed baking sheet with parchment or a silpat.
Chop or dice the onions to your preference.
onions
Place the onions on the baking sheet and move them around so they aren't too clumped up, and place the tray in the freezer. Freeze for 3 hours.
Break apart any clumps that have formed on the baking sheet and transfer the onions to freezer-proof storage.
How to Freeze Onion Rings/Strips
Drop the sliced onions into boiling water for 15 seconds.
Once the time is up, strain the onions through a colander and immediately add to a bowl of ice water for two minutes.
Strain again and set aside to drain. Allow onions to dry on a clean towel.
Place on a rimmed baking sheet lined with parchment and freeze for 3 hours. Transfer to freezer storage.
How to Freeze Whole Onions
Blanch small onions for 3 minutes and large onions for 7 minutes.
Once the time is up, strain the onions through a colander and immediately add to a bowl of ice water for five minutes.
Strain again and set aside to drain. Allow onions to dry on a clean towel.
Place on a rimmed baking sheet lined with parchment and freeze for 5 hours. Transfer to freezer storage.
Notes
If you have a lot of onions to freeze at once, lay another piece of parchment on top of the onions and top with an additional layer. Make sure you're using sturdy freezer-safe storage to keep the onion smell contained.Frozen onions will last in a conventional freezer for six months or a deep freezer for a year.If onions make you cry, chill whole onions in the fridge for 1 hour prior to cutting.