Preserving herbs in salt is really only a method of dehydration as the salt slowly sucks the moisture from the leaves. Layering herbs in salt is a technique that I have long used for sage. While the individual leaves do dry out over time, for at least a year, they retain their pliable, leathery texture and become a little less stringent than fresh sage. This method is so effective that I scarcely notice the difference from using fresh sage.
The trick is to layer the leaves so that they are surrounded by salt and not touching each other. Otherwise, the leaves could become moldy. I use Kosher salt since it contains no iodine and actually re-use the salt year after year. As with vanilla sugar, it takes on a slight taste of sage so when I’m choosing a few leaves to toss into a dish in the winter, I also use a pinch or two of the salt.
Typically, I have used a large Weck canning jar with a tightly clamped lid, but the shape has not been so useful. This year, I layered the leaves in a flat glass baking pan with a plastic lid. I will store it in a dark pantry cupboard. When I posted a soup recipe that was garnished with salt-cured sage a few months ago, Doris and Jilly Cook asked if this technique would work with other herbs and I surmised that it would, especially for the woodier herbs like rosemary and winter savory. So next up will be an experiment with those herbs, which I’ll submerge in the Weck jar and let you know what happens.