I was putting up a bunch of these today and thought that some of you Serious Eaters might be interested in trying them. I started with five pounds of Mayan Sweet onions, peeled then sliced them thin in the food processor (using a mandoline or hand slicing works just fine too) and put them in the crockpot on low for about 24 hours. Set the heat up to high for an additional four hours until they were nice and brown then cooled and packaged for freezing. From the initial five pounds I got 3-1/2 cups of caramelized onions that I packaged in 1/2 cup portions in snack size zip bags and froze. This takes into account the many, many spoonfuls I had to try during the process just to be sure they were cooking properly (what can I say? I love onions).
Uses for these guys are limited only by your imagination but we spread them on sandwiches, mix them with butter and herbs to melt on steak, add to beef broth for a very quick onion soup, mix them into scrambled eggs, use them for fajitas and quesadillas, well, you get the picture. If you're of a mind, you can also add sliced or chopped peppers into the mix. I've been thinking I might try adding fennel one of these days as well.
These can also be pressure canned but they take up so little room in the freezer, I just find that more convenient.
And if you're working a new year's resolution to lose a few pounds, there's absolutely no fat or salt but a ton of flavor. What's not to like about that?