The Israeli zaatar will mainly bring a mix of oregano, thyme, marjoram,salt and sesame seeds. Sumac is added to some family recipes coming from Lebanon, and some from Palestinian recipes, as I learn form some websites, can come with caraway seeds. As with well kept family recipes, each Za'atar can have its own variations depending on the creativity and background.
Yam with Za'atar
I use always the small orange yam or sweet potato, but I believe it can also work with white sweet potatoes or even butternut squash.
6 medium jewel yams or sweet potatoes
1 tablespoon water
Kosher salt to taste
1 tablespoon olive oil
1 tablespoon za'atar
Cook yams or potatoes on microwave in the baked potato mode with the water on the bottom of the pan, counting each 2 yams as one potato. After ready wait about 15 minutes and heat olive oil in a shallow skillet. Cut each yam in half and sprinkle both sides with salt and za'atar. Leave it to golden each side for about 5 minutes.