Toast sesame seeds in a small skillet over low, stirring occasionally, until fragrant and lightly toasted, about 5 minutes. Transfer sesame seeds to a small plate, and let cool slightly, about 5 minutes. Set aside.
Grind za’atar leaves, sumac, and salt in a spice grinder until coarsely ground, about 15 seconds. (Alternatively, crush using a mortar and pestle.) Pour into a small bowl; stir in toasted sesame seeds.
