Pours boiling water into the jars just as she is about to fill them to heat them. Then she pours out the water, fills them with very hot filling all the way to the top, closes them tightly, and turns them upside down. They kinda vacuum seal themselves as they cool, and the ones you can see did not seal, she puts in the fridge.

*******disclaimer********

I can't vouch that this is as safe as a water bath or pressure cooker, but she has been doing it for 35-40 years. Just thought I'd share.