Q&A for How to Freeze Onions

You can, but they will be harder to slice after freezing - too hard when frozen, too mushy when thawed.

Yes, but as this article suggests, they should be drained, spread flat and frozen before you put them in freezer bags. Don't chop them too small. Quartering an onion (depending on the size of the onion) is probably the smallest you should do. If they are any smaller, you may lose some of the "fresh" flavor of the onions. Cooking thoroughly may lessen the flavor also. Blanching the onions usually works better in keeping the flavor.

Yes, you can. I usually look up the safe handling directions, but nearly any food can be frozen using a Seal-A-Meal. However, soups should be frozen in an approved freezer container. If you have the attachment for your Seal-A-Meal that will remove the air from the container, your soups will stay fresher for a longer period of time.

You shouldn't put whole onions in the freezer. Once thawed they are useless. I wouldn't use them after that.

I would assume "up to 6 months," as online instructions say regarding freezing onions.

Yes, you can cook with them from a frozen state. They will contain excess water, so fry them off on their own until the water has evaporated if you feel like it. I would not suggest defrosting onions to use raw, because the texture and flavor are different from fresh onions.