Tteok is largely divided into four categories: "steamed tteok" (찌는 떡), "pounded tteok" (치는 떡), "boiled tteok" (삶는 떡) and "pan-fried tteok" (지지는 떡). The steamed tteok is made by steaming rice or glutinous rice flour in "siru" (시루), or a large earthenwaresteamer, so it is often called "sirutteok" (시루떡). It is regarded as the basic and oldest form of tteok. Pounded tteok is made by using a pounding board or mortar after steaming it first. In making pan-fried tteok, the rice dough is flattened like a pancake and pan-fried with vegetable oil. Shaped tteok are made by kneading dough with hot water, then shaping it into balls.