Sumac vs Za'atar herb
The short answer
One is an ingredient of the other, and both are called za'atar in different contexts. Za'atar the herb is a wild Middle Eastern relative of oregano, thyme and marjoram. Za'atar the blend is that herb with sesame, salt and usually a good deal of sumac. Sumac on its own is the sour red drupe. A recipe calling for za'atar almost always means the blend; one calling for sumac means the single souring spice, and using the blend instead adds herb, sesame and salt the dish did not ask for.
Side by side
| Sumac | Za'atar herb | |
|---|---|---|
| Botanical identity | Rhus coriaria L. | Origanum syriacum L., Thymbra spicata L., Satureja thymbra L., Thymus capitatus (L.) Hoffmanns. & Link |
| Part used | fruit, berry | leaf |
| Origin | The Mediterranean basin and West Asia, with the plant growing wild across a broad arc from Sicily through Anatolia to Iran. | The eastern Mediterranean and the Levant, where the plants grow wild across dry rocky hillsides from Turkey to Palestine, Lebanon, Syria and Jordan. |
| Flavour notes | sour, fruity, tannic, astringent, bright | herbal, woody, bitter, earthy |
| Heat | Scoville does not apply | Scoville does not apply |
| Flavour | Sharply sour with a fruity, almost cranberry-like character and a tannic, mouth-drying finish. The sourness is clean and lingering, without the sharp immediacy of vinegar, and unlike lemon it brings no bitterness from peel and no liquid at all — which is exactly why it is used where a wet acid would ruin the texture. | Savoury, herbal and slightly bitter, more astringent and less sweet than Mediterranean oregano and more rounded than thyme alone. It is not sour — the sourness in the blend is sumac — and it is not hot. On its own it is quieter than people expect, which is much of why it is nearly always used with sesame and salt. |
| Aroma | Faint. A light fruity, slightly resinous smell with a tannic edge, but sumac is nearly silent in the jar compared with the aromatic spices, and its aroma is not what it is for. | Warm, herbal and distinctly thyme-like, with an oregano roundness behind it and a faint mineral dryness. It smells of hot dry hillside rather than of a garden herb, and it releases far more on being rubbed than on being opened. |
Which should you buy?
Sumac
This is the one common spice where the usual "buy whole" advice mostly does not apply. Whole sumac drupes are hard to source outside Middle Eastern grocers and awkward to grind well, because the aim is to mill the flesh while excluding the hard seed — which is a job for a mill and a sieve, not a domestic grinder. Buying ground is the normal and reasonable choice. Spend the effort instead on buying unsalted sumac from a supplier that states its origin, and on buying small quantities often, since colour is what fades.
Za'atar herb
Buy it rubbed rather than ground, and buy it from a Levantine grocer if you can, where the herb is sold separately from the blend and both are fresher and cheaper than a supermarket jar. The real buying decision here is not the form but which ingredient you are actually after: a great many recipes written in English say za'atar and mean the blend, and a jar of the plain herb used at the same quantity will taste thin and unsalted. If a recipe lists za'atar alongside sesame and sumac, it means the herb.
Full detail on sumac and za'atar herb, including evidence grades and sources for every claim above.