We get a lot more onions from our garden than we can use before they spoil, so we chop them and freeze in ziploc bags. I was pleasantly surprised last week when I sauted some for soup, it worked really well. And wonderful to have on hand when you need some!
We do this too. It's nice to have "fresh" veggies when you need them. I also save lots and lots of unused veggies this way, and whenever I make some sort of veggie or Minestrone soup, I pull out the bag full of frozen veggie scraps and toss those in. Great way to reduce out waste!