I regularly can jams and jellies; doing so does not require the hot bath canning method. I recently canned some Caramelized Onion Jam with Balsamic Vinegar the same way I would a jam or jelly (namely, putting the hot mixture in the hot jars, tightly sealing and letting cool upside down. All seemed to seal, as -- after cooling -- the tops didn't flex) but now I'm worrying. Knowing that nasty food poisoning (can you say botulism?) can occur with improperly canned foods. Is there any reason why Caramelized Onion Jam with Balsamic Vinegar (vinegar for flavoring; it isn't drenched) shouldn't be canned the same way as more traditional fruit jams and jellies?
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