I would think
that caramelized onions should freeze well for a few weeks since there is not really a texture change issue.
I used to do a lot of make ahead one day a week cooking (there are a lot of Once A Month Cooking OAMC websites
with good information and ideas) ... especially when I was in college, working nights when I had to take my own meals or putting in a lot of overtime and didn;t have time to cook every day, and when I was taking care of my step-mother (I would prepare and freeze her meals and then all she had to do was heat them in the microwave when she was ready to eat).
The National Center for Home Food Preservation
has a good section on "How Do I Freeze?
" that covers most of the bases - and a lot of what I have learned from trial and error over the years. The General Information
section covers what will/will not freeze well, what changes occur with certain things, and even includes the changes that happen with spices and seasonings, like:
- Pepper, cloves, garlic, green pepper, imitation vanilla and some herbs tend to get strong and bitter.
- Onion and paprika change flavor during freezing.
- Celery seasonings become stronger.
- Curry develop a musty off-flavor.
- Salt loses flavor and has the tendency to increase rancidity of any item containing fat.
- When using seasonings and spices, season lightly before freezing, and add additional seasonings when reheating or serving.
The University of Georgia Cooperative Extension Service has an excellent paper on Freezing Prepared Foods
that also has a lot of good information on freezing, thawing and reheating frozen ingredients and prepared meals.