This is based off a middle eastern bakery item called meneish, it's great, especially fresh, but not very accessible.
Za'tar is a combination of dried herbs, sesame seeds, sumac, and usually a little salt. It's often served mixed with olive oil, but it's a little heavy with all the oil, yogurt lightens it up, brings out the sour tones, and brings in a creaminess.
When buying za'atar, look for something more green in color, there are variations that are more brown, but the green has a better flavor profile, (in my opinion) it's fresher and lighter in flavor.
How to make this, I like to use non-toasted bread, top it off with strained yogurt and then za'atar, try not breathe hard, laugh, sneeze, that kind of thing the za'atar just flies off.
1 slice bread
2 tbsp strained yogurt
1 tbsp za'atar