Pita Gyros me Mustarda is the standard pita gyros with mustard added, mustarda, sometimes requested on its own and, in much of northern Greece, part of the regional baseline alongside ketchup. The angle here is precise: what a line of mustard contributes to the sauce balance of a gyros, and how a good shop doses a sharp condiment so it sharpens the round instead of taking it over.
The build is the usual order with mustard worked into the sauce layer: warm griddled pita, tzatziki and a stripe of mustard on the bread, carved gyros off the spit, tomato, onion, fries, rolled into a cone. Mustard's job is acidic, pungent bite cutting straight through the fat of the meat and the richness of the tzatziki, a sharper, drier counterpoint than ketchup's sweetness, which is why the two often appear together in the northern style. Good execution runs it as a thin stripe so it threads through each bite rather than dominating; in the Thessaloniki-style build the tzatziki is frequently reduced or dropped because mustard and ketchup are doing the work of cutting and seasoning. Sloppy work over-squeezes a harsh, vinegary mustard so it overwhelms the meat and turns every bite into one searing note, or it pairs a full load of garlicky tzatziki with mustard so the two sharp sauces collide instead of layering. The structure is unchanged, soft pita, tight roll, sealed base, but mustard is potent, so the failure mode here is almost always dose, not leakage.
This variant exists because mustard is a genuine, regionally standard choice on a Greek gyros, especially in the north, not an oddity, and it cleanly tests whether a shop can balance a pungent condiment against fat and salt. Some counters treat mustard and ketchup as the default pair and serve tzatziki only when asked; others keep tzatziki primary and add a measured line of mustard for the people who request it. The northern gyros thessalonikis, where mustard belongs to the standard formula, deserves its own article rather than being crowded in here; at this entry the single variable is the mustarda and whether its sharpness was dosed to lift the wrap rather than dominate it.