Cretan Boureki is a Cretan zucchini-and-potato pie: thin rounds of zucchini and potato layered with cheese, bound lightly, and baked in a low pan until set. It belongs on this catalog as a pita-family relative rather than a sandwich proper, and it is worth being honest about that. There is no folded bread around a filling here; it is a baked vegetable pie, cut into wedges, eaten warm or at room temperature. The interest is in how spare it is: a few ingredients, a long bake, and a result that tastes squarely of summer vegetables and Cretan cheese.
The build runs in layers. Zucchini and potato are sliced thin and even so they cook through together, salted to draw water so the finished pie is not soggy, then arranged in alternating sheets with a fresh, slightly sour Cretan cheese (often mizithra or a feta-style cheese) and mint scattered between. Some versions sit the layers on a thin sheet of phyllo or a simple flour-and-water crust; many skip the pastry entirely and let the vegetables and cheese form the body. A light dusting of flour between layers and a slow, moderate oven bind it into something you can cut clean. Good boureki holds its slice, the potato fully tender, the zucchini collapsed but not watery, the cheese melted into the seams. Sloppy versions show under-salted zucchini that floods the pan, potato still firm in the center because it was cut too thick, or so much cheese the vegetables disappear. Mint is the quiet correction that keeps the richness honest, and it should be present without taking over.
Variation is mostly about the crust question and the cheese. A pastry-wrapped version eats closer to a pie; the crustless one eats closer to a gratin, which is the more common Chania-style form. The cheese shifts the whole character: a sharper, saltier one cuts the vegetables, a milder fresh cheese lets them lead. It is not the same thing as the small filled pastries called kalitsounia, which are their own Cretan preparation and deserve their own article rather than being crowded in here. Served warm it is a meal; cooled and cut the next day it holds up well, which is part of why it is made in a wide pan.