one of my current favourite ingredients is really more a group of products that goes under all manner of names. Qorot, kishk, jameed or tarhana (to list just a few of the options) is, essentially, made from fermented yoghurt, milk or whey, and is common in Afghanistan,Iranian, Turkish, Balkan and Arab cuisines. Its popularity derives from a depth of umami flavour similar to that you might find in a mature cheese such as parmesan.
The Persian "Qorot" is a preserved food made from Yoghurt or barley mixed with sour milk or yoghurt; in Afghanistan and Iran, however, the same word also means dried buttermilk. Qorot comes in liquid or dried form (you reconstitute it with water), and is traditionally made with the milk left over from cheese-making.
In Lebanon, Syria, Palestine, Jordan, Turkey and Armenia, "kishk" is the name given to preserved discs of fermented yogurt and wheat. At the end of summer, just after the wheat harvest, bulgur is made by boiling, drying and crushing the grain. This is then mixed with the yoghurt, spread on a tray and left until the grain has absorbed all the liquid. The kishk grains are then spread on cloths and left to dry in the sun; a final rubbing reduces them to a powder. Other takes on the theme don't involve grain at all, just blocks of dried, fermented yoghurt, which are crushed and then reconstituted.