Sumac is acid without liquid. It sharpens a dish without thinning it — a problem citrus juice creates every time you use it on something that’s already right in texture. A pinch on roasted vegetables, on grilled chicken, on fried eggs, on hummus — it does what lemon does but leaves the dish exactly where it was.
When something is almost right but flat, the answer is usually one of three things: salt, acid, or fat. Sumac is my fastest route to acid. It goes on at the end, after the heat, because heat dulls the sour notes and you want them bright.
It’s the answer to “it needs something.” Most of the time, it is.