Preheat the oven to 350 F.
1. Put the sesame seeds on a small sheet pan or pie plate and toast for 6 minutes, until golden brown.
2. Combine thyme, sumac, salt, and sesame seeds and grind into a fine powder in a spice mill. (This may need to be done in 2 batches.)
*Store in an airtight container for up to 3 to 4 months. Refrigeration is not necessary.