If you can’t find za’atar in the store, you can make your own mix by stirring together: 1/2 tablespoon dried thyme, crumbled, 1/2 tablespoon dried oregano, crumbled, 1 tablespoon cumin, ground, 1/2 tablespoon coriander, 1 tablespoon toasted sesame seeds, and 1 tablespoon sumac (sumac is optional but gives a nice tart and lemony flavor). Store in a dry place for up to 3 months.