The onion will look like this now. We spread the onion out a little more then it normally would be so you can see the slices.
I have never had very good luck with storing onions no matter what I tried until I hit on this method, and it sure works for me. (This process only works for onion used as chopped or ground, such as in meat loaf, chili, and spaghetti sauce, slow cooking roasts, etc. It does not work for sliced onions on hamburgers or onion slices for deep frying.)
At harvest time, I divide the work load into manageable parts, such as pulling onions one day, cleaning off tops and dirt the next day preparatory to getting them into the kitchen; peeling the skins the next and storing overnight in zippered refrigerator bags, chopping into segments that will fit into my grinder the next day, and so on. It all depends upon how many onions we have in the harvest.
Set your own schedule as to how best it works for you. There is no other ingredient you need to add to the onions for the freezing process.
I prefer to use a small electric chopper or grinder but if you prefer to hand chop, then that's what works best for you. As I grind the onion down into tiny bits, I pack the onion bits and resulting juice (there will be some) into pint-sized freezer bags, pressing out all the air I can to make them very flat.
After they are at this stage, I can spread out 6 or 7 bags of onions on a large cookie sheet and freeze fully. When fully frozen, these bags stack beautifully up the side of the chest freezer inside plastic or brown paper grocery bags. I pack all individually frozen packages into the plastic bags and then put those in the brown paper bags to make doubly sure I won't have onion smells permeating anything else.
When I want onion for a recipe, I take a bag out of the freezer, estimate or "eyeball" how much I need, whack the top portion of the frozen onion bag against a countertop edge, and take what I need. It won't be an exact measurement but I can get it close enough. The bag is back into the freezer in less than 60 seconds, waiting for the next time I need onion without storing, peeling, or chopping.
By ronsan from southwest Missouri