The Best Way to Open a Naughty Jar When All Else Fails
As you probably already know, keeping the can lid under hot water can help, but some lids need to be exposed to heat longer for it to actually work. So when anything does not help , Sarah Jampel of Food52 recommended to try this trick:
Turn the jar upside down, submerge it in a bowl of hot water for a minute or two, and then use the forced draft method to open it.
You may need to refresh the water several times with lukewarm water for it to work — to keep it warm — but eventually it must budge. With enough patience, no pot can beat you.