The unwaxed lemons of all shapes and sizes are homegrown at my parents' farm. Rick Stein recommends 3-4 small lemons per 500ml jar.
Other than lemons, all you need is 75g salt per jar.
Slice the lemons into quarters but leave them attached at the stalk.
So they'll look like this:
Fill the cuts with salt.
Squish each lemon into the jar, and sprinkle over the remaining salt.
You'll fit in more than you think! I used a 700ml jar, and in that fit four larger lemons.
The salt will fall to the bottom of the jar, and it will draw out the juice from the lemons.
With the lid on, Rick says to shake the jar occasionally for four-to-five days and then top it up with more lemon juice (that will be part two, a week or so from now) then, after a couple of weeks, they should be ready to use. My tips would be don't attempt this if you have any cuts on your fingers (ouch!) and select jars with wide mouths, otherwise you'll end up with the situation shown below; no matter how hard I tried those little suckers were not going into that sauce jar!