I had a friend that worked at Bird's Eye where they froze vegetables. He told em that there are two keys to the processes-make sure the onion is a dry as possible (after you dice it up make sure to towel dry the pieces as dry as possible) and then get them to freezing quickly. A normal refrigerator freezer will not do this-what we do is get dry ice, put the green peppers, onions and other types of veggies in freezer bags and then drop them into the dry ice chest until the individual pieces start to set up-then move them to the frig. freezer.