Not a bad staple for any pantry.
Scrub 10 lemons well and cut into quarters. Place in a bowl and mix well with 250 gm kitchen salt. Put a layer of salt in a clean preserving jar and pack the lemons in, skin side out, pressing on them firmly to release juices as you do so.
Top up the jar with extra lemon juice to cover the lemons, seal and leave for a month or so before using. They will last in the fridge for 2-3 months.