Celery salt is an savoury seasoning that sounds familiar to me but I don’t recall trying before. However, after a bit of random searching the other day, it turns out there’s not much more to it than the name suggests. The method I discovered involved cutting the leaves off the celery (which I frequently discard to the compost pot), dehydrating them and then mixing in equal quantities with salt.
My dehydrator has been idle for a bit as there isn’t much to harvest in our garden during the winter. I did have some celery with leaves in the fridge though so I got it running and, once the leaves dried enough to crumble between my fingers, I mixed them with some salt. Probably a bit too much salt but initial impressions are good and, next time I get some celery, I’ll get a few more leaves dehydrated to add in (I think the page I found suggested you can just keep your little pot topped up).