What is
Quark is a type of fresh dairy product, common for the cuisines of German-speaking countries made by warming soured milk until the desired degree of coagulation (denaturation, curdling) of milk proteins is met, and then strained.
Feta cheese, a type of Greek cheese, is made from milk that is brined or pickled. The process of brining gives a tangy, salty and a crumbly consistency to feta cheese.