I usually chop up the unused onion, spread it on a cookie sheet and freeze it for about 20 minutes. Then I put it in a freezer bag and return it to the freezer. I can take out what I need for omlets, etc. Better than buying the already frozen, chopped onions!
But if I know I'm going to use the remainder of an onion soon, I just store it in the fridge.
Last edited by lovelyl; 10-09-2016 at 04:32 AM.