As a home cook I make large batches of caramelized onions, then freeze them flat in quart size ziplock bags. They freeze great and you can easily break off a chunk. I generally break off a 2 inch chunk of onion, finely dice while they are still partially frozen, then thrown them in my dish. It saves so much time prepping for dinner. They have never been mushy. I follow the same set up for roasting chili's and freezing them for later to save on prep time.
10/25/11 at 6:47am