On Sunday, 8 November 2020 14:43:00 UTC, michael adams wrote:
And er, turn the jar.
You can always get a better grip on a glass jar simply
with the width of your hand, given which it seems to
make more sense to turn the jar rather than the lid.
Which still needs to be gripped firmly, but not turned
at the same time.

On a few occasions I've used a small nail* to put a hole in the lid and release the vacuum.

Obviously this only works on things which are going to be consumed quickly where the jar is not needed to reclose, although a blob of insulation tape* can close the hole for a few days.

*I'm sure /we/ all have such things in our kitchens.

Owain