Falafel b'Saj is the falafel sandwich rolled in saj bread, named for the dome it is baked on. Saj is the very thin, large, pliable flatbread cooked on a convex metal griddle, and the b' marks that the falafel is wrapped in it. The angle is the bread's thinness. Saj is closer to a delicate sheet than to a pocket, so it rolls tight around the filling and almost vanishes, which makes this the leanest, driest-eating version of the falafel wrap and throws even more weight onto the fritter and the sauce.
The filling is the standard Lebanese falafel. Soaked chickpeas, often with fava, ground with parsley, cilantro, onion, garlic, cumin, and coriander, shaped small and deep-fried to order so the outside crackles and the inside stays tender and green. The fritters are arranged along a sheet of saj, then dressed with tahini loosened by lemon and water, tomato, cucumber, parsley or mint, onion, and pink pickled turnips, sometimes a chili paste. The bread is rolled into a tight, slender cylinder, often pressed briefly on the hot griddle so it warms and the seam sets. Because saj is so thin and carries little moisture of its own, the balance of sauce matters more here than in a thicker wrap. Good execution fries the falafel fresh so it stays crisp inside the snug roll, keeps the tahini tangy and measured so the thin bread does not turn to paste, and rolls it tightly enough to hold its shape. Sloppy execution over-sauces until the fragile saj tears and weeps, wraps soft pre-fried fritters that go greasy, or rolls it slack so the filling spills the moment it is bitten.
It varies mostly by how the saj is finished and by the fry, since the bread is what sets it apart. Pressed back on the griddle the wrap takes on a faint toast and a little crispness at the seam; left unpressed it stays soft and supple. The directly related forms differ only in bread: the same falafel in soft Arabic khubz as falafel b'khubz, or stuffed into a pocket pita. Eaten in the morning it serves as breakfast like the others. What holds constant is the point of the name: falafel in thin griddle bread, a wrap built to be light and tight, with the crisp fritter, the sour turnip, and the nutty tahini doing nearly all the work the bread chooses not to.