Ask Ottolenghi: what’s going wrong with my preserved lemons?

I’ve been using and preserving lemons since reading the Jerusalem cookbook. But how do I prevent them from floating?
Agata, Stockholm, Sweden
It’s great you’re preserving your own, but sorry to hear you’ve got floaters! The key is to really pack your lemons into the jar; so long as they have a bit of “give” (you know how some lemons can feel rock hard?) you should be able to push them into all the “corners” of the jar, so there’s no room for them to move about and rise up. The jar needs to be sterilised, too, as I’m sure you know – just putting it through a dishwasher will do the job. Also, the liquid surrounding the lemons should contain absolutely no water, just lemon juice and salt.

If you think they might still rise up, you can always add a weight to hold the lemons in place and keep them submerged. Either buy pickle (AKA fermentation) weights or, just as good, improvise by putting a smaller jar filled with water (and the lid screwed on tight!) on top of the lemons to hold them down. (Again, make sure the small jar is sterilised to prevent the possibility of the lemons spoiling.) Otherwise, a small plate could do the job.

Finally, just before you seal the jar, give it a gentle but firm tap on a well-cushioned work surface – I use two or three folded tea towels to create a cushion. (Take care here because, obviously, banging a glass jar on a hard surface could result in the complete opposite of preserving.) This final step will ensure that there are no air bubbles in the jar, which might well be what’s causing your lemons to float in the first place. Good luck, and well done for sticking with it.