An — The Soul of Japanese Confectionery

An (餡 — sweet bean paste) is the foundational ingredient of Japanese confectionery in the way that crème pâtissière is the foundation of French patisserie — a base from which an entire system of preparations extends. Its preparation from azuki beans (小豆 — literally "small beans") or white beans (白花豆) appears in Japanese culinary records from the eighth century CE, when it was brought from China as part of Buddhist temple food culture. The technique of sweetening and working the paste reached its current form during the Heian period. There is no equivalent in Western confectionery — a paste made from legumes, sweetened, and used as a primary filling for sweets is entirely outside the Western tradition's experience.

An is made from dried azuki beans simmered until fully soft, then worked with sugar to a specific consistency. There are two primary forms:

An pairs with matcha because their flavour profiles are complementary counterpoints: matcha is bitter, vegetal, umami-forward; an is sweet, earthy, mineral. Together they produce a complete flavour experience that neither achieves alone. The pair is ancient — it has been the foundation of the tea ceremony for four hundred years — and it is correct.