Trahana is made from wheat flour (usually a coarse semolina or a bulgur) kneaded with milk. If the milk is fresh, it’s sweet trahana. If the milk is soured, it’s sour trahana. Sour trahana uses buttermilk, yogurt. Alternatively, fresh milk can be used and the pasta can be left to naturally sour in the sun for a day or two, although most people who don’t buy theirs probably dry it in the oven.