Donkey rolls, also known as bean flour cake, is one of the ancient varieties of Beijing snacks, its raw materials are steamed with yellow rice flour and water, and flour slightly more water and soft. Another will be fried soybeans, rolled into powdered noodles. When making the steamed yellow rice flour outside the soybean flour surface rolled into a skin, and then smeared with red bean paste filling (also available in brown sugar) rolled up, cut into small pieces of about 100 grams, sprinkled with sugar on it. The filling is required to be rolled evenly, with distinct layers and a yellow appearance, characterized by fragrance, sweetness, stickiness, and a strong flavor of soybean flour. Soybean flour cake with soybean flour as its main raw material, so it is called soybean flour cake. But why also known as "donkey roll"? Seems to be a figurative analogy, after the production of soybean flour in the roll, such as the countryside really donkey roll, raising dust like, so it is named. Nowadays, many people only know the name of the common name, do not know its proper name. Now the snack bar year-round supply, but most have not used yellow rice noodles, switching to river rice noodles, because the outer roll soybean flour noodles, the color is still yellow, is a very popular snacks.