Za'atar is a Levantine seasoning blend built from dried wild thyme or oregano, tangy crimson sumac, toasted sesame seeds and salt. Herbal, nutty, tart and savoury all at once, it is the everyday condiment of the eastern Mediterranean — stirred into olive oil and swiped onto warm flatbread, dusted over labneh and hummus, and rubbed onto roast chicken and vegetables.