Preserving fruits is so cool.

Preserved lemons are great and they last for yonks. If you don't get enough juice you can just top up with salted water, boiled and cooled.

I never actually cut them into quarters, just cut two slits down the middle, like they do in Morocco, so they are almost quartered, but still hold together. 500g jars are a bit small, though, it's much easier to use bigger ones and cram a load more lemons in.

 pretty tasty marmalade using the lemons.

Some recipes call for removing and discarding the white pith, but that always seemed like too much work. I don't mind a slightly tart marmalade, so just use the whole fruit cut into slices.

I've found an electric slow cooker in sauté mode with the top off works really well

to cook the marmalade.

It has good insulation and temperature control, making it harder to burn the marmalade.