Step 1

Place thyme leaves on a baking sheet in a 300°F oven until dry, just ten minutes or so. Just long enough that they'll crumble between pinched fingers after cooling. Allow to cool completely.

Step 2

Use a mortar and pestle to grind the thyme leave finely. If your thyme is at all stem-y or fibrous, sift to remove any larger particles. Transfer to a small bowl, and aside.

Step 3

Crush the sumac finely with the mortar and pestle, add the salt and crush with the sumac. Add the thyme back, and grind together a bit. Stir in the sesame seeds, taste, and adjust to your liking, perhaps with a bit more salt, or sumac, or sesame seeds. Any za'atar you might not use in the coming days keeps best refrigerated (or in the freezer) if you make a double or triple batch. Or in a light-safe container on your counter for daily use.