Tsubuan

Tsubuan (粒あん) is a traditional Japanese sweet paste made from azuki beans. It is the coarser form of anko, retaining visible beans rather than being fully puréed. The beans are typically simmered with sugar until tender, then mashed only partially so that many beans remain whole or partially crushed, with the skins generally still present.

The preparation emphasizes texture as well as flavor: beans are soaked, boiled, and mashed using a suribachi and pestle or a grinder, then sweetened and simmered to adjust moisture and consistency. The resulting paste is darker and denser than smooth koshi-an, and its sweetness levels vary by recipe or region.

Tsubuan is widely used in wagashi, including daifuku (mochi filled with tsubuan), manju, and dorayaki, as well as in sweet buns like anpan. It is chosen when a more robust bean flavor and a chunkier mouthfeel are desired.

There are regional and maker variations in bean size and sugar content. Some tsubuan contain larger, more intact beans, while others are somewhat finer but still perceptibly granular. The paste can be refrigerated for several days or frozen for longer storage.