Japan — zenzai (善哉) is said to take its name from the Buddhist exclamation 'zenzai' ('excellent', 'well done') spoken by the monk Ikkyū upon eating the sweet bean soup. Azuki sweet soup preparations appear in Japanese cooking texts from at least the Heian period. The Kyoto winter zenzai tradition is closely linked to the Yasaka Shrine's okera-mairi (New Year's fire ceremony) where attendees walk through winter streets with lanterns and warm themselves at teashops serving zenzai.
Zenzai (善哉) and shiruko (汁粉) are Japanese sweet soups of azuki red beans and mochi or dango, eaten as both dessert and as a warming winter drink. Zenzai uses tsubuan (chunky, whole bean) paste in a thicker soup with grilled mochi; shiruko is a thinner soup made from smoother anko (koshian) that liquefies into a flowing consistency. Both are served with a small plate of shiokombu (salt-pickled kelp) or a few shiokonbu-tsuke pickles — the salted element is essential to offset the soup's sweetness and reset the palate. Zenzai is a speciality of Kyoto wagashi culture, particularly associated with the Yasaka Shrine and served at teashops along Higashiyama. Shiruko with mochi is a winter staple at traditional tearooms nationwide.
Zenzai's flavour is a specific sweetness — not the sharp, clean sweetness of sugar but the earthy, complex sweetness of slow-cooked azuki beans, which have their own tannins, starch character, and a subtle earthiness that gives the soup depth. The mochi adds a neutral starchy chewiness that provides relief between spoonfuls of the intense bean soup. The shiokombu or pickles' clean salinity creates the crucial reset — without it, the sweetness accumulates and becomes fatiguing.
Azuki cooking for zenzai: sort and wash dried azuki; boil 5 minutes and discard first water (removes harsh tannins). Cover with fresh water; simmer 60–90 minutes until beans are fully tender but holding their shape (for tsubuan). Season with sugar (add late, not during cooking — sugar toughens beans if added too early) and a tiny pinch of salt. The soup should be neither watery nor solid — flowing slowly but with visible whole beans. Serve in lacquered bowls with grilled mochi on a separate plate placed beside; the diner adds the mochi themselves, which softens gradually in the sweet broth.
The optimal zenzai balance has a slight bitterness from the azuki beans underlying the sweetness — this comes from proper cooking (the initial boil-and-discard removes harsh tannins but not all bitterness). Zenzai that is pure sweetness without any azuki character is over-processed or made from inferior beans. Dainagon azuki (大納言小豆) — a larger, premium variety of azuki from Kyoto — is the correct bean for zenzai; it holds its shape better than ordinary azuki and has a more complex flavour. Served alongside a small piece of mochi toasted on charcoal (the surface lightly charred), the mochi's faint smokiness against the sweet bean soup creates the Kyoto winter teashop experience.
Adding sugar too early — sugar added to cooking beans prevents them from fully softening; always add only after the beans are tender. Over-sweetening — zenzai should be moderately sweet; excessive sugar creates a cloying, one-dimensional result. Forgetting the salt element (shiokombu or pickles) — the salt counterpoint is essential to the eating experience.
The Wagashi Book — Naomi Moriyama; Washoku — Elizabeth Andoh