-
1
Place the sorted, rinsed adzuki beans in a saucepan and cover generously with cold water. Bring to a full boil and cook for 5 minutes. Drain and discard this first cooking water entirely — this is the shibori step, removing the bitter saponins that would otherwise cloud and astringent the finished soup. The water poured away will be noticeably dark.
-
2
Return the drained beans to the pan and cover with fresh cold water by at least 5 cm. Bring to a gentle simmer and cook, partially covered, for 60–90 minutes, adding water as needed to keep the beans submerged. The dish lives or dies at this stage: the beans must be completely, unresistingly tender — press one between the fingers and it should collapse to a smooth paste with no grainy core — before any sugar is introduced. A bean with any firmness remaining will harden irreversibly once sugar is added, producing a grainy texture no subsequent cooking can correct.
-
3
For smooth shiruko (Kanto style): pass the fully cooked beans and their liquid through a fine-mesh tamis or drum sieve, pressing firmly to extract a silky purée. Discard the skins. Return the strained liquid and paste to a clean pan, add the sugar, and stir over low heat until the sugar is fully dissolved and the soup is cohesive and uniformly smooth. For chunky zenzai (Kanto style): retain the whole beans in their cooking liquid, add the sugar, and stir over low heat until dissolved and the beans are evenly glazed in the sweet liquor. In either case, the soup should coat a spoon lightly and appear a deep mahogany red.
-
4
Add a small pinch of fine sea salt to the finished soup and stir once. Taste: the salt should not be perceptible as such but should open the adzuki flavour and relieve any sense of monotonous sweetness. The soup is now complete. Keep warm over the lowest possible heat.
-
5
Combine the shiratamako with cold water added gradually, working the dough by hand until it is soft, smooth, and just barely non-sticky — the texture of an earlobe is the traditional test. Roll into balls of approximately 2 cm diameter. Drop into a pot of boiling water and cook until the balls rise to the surface, then continue for a further 1 minute. Remove with a slotted spoon and transfer immediately to cold water to arrest cooking. The dango are ready when firm to the touch on the outside but yielding within.
-
6
Ladle the hot adzuki soup into warmed bowls — lacquerware for ceremonial service. Drain the shiratama dango and place two or three in each bowl. Serve at once: the mochi provides the chewy, neutral textural counterpoint that defines the dish against the velvety bean medium.