Japanese Zōsui Rice Soup and Its Distinction from Okayu

Japan — zōsui tradition from Heian period as a poverty food (stretch leftover rice with broth); elevated to a prized nabe ending dish during the Edo period when nabe culture became a social institution

Zōsui (雑炊 — 'miscellaneous cook') is a comforting rice-in-broth dish that is fundamentally different from okayu (rice porridge) in its starting point and result. Okayu is made from raw or soaked rice cooked in a large quantity of water from the beginning. Zōsui is made from previously cooked rice added to a flavoured broth — typically the remaining broth from a nabe (hot pot) at the end of a meal. The cooked rice grains are rinsed briefly in warm water before adding (to remove surface starch that would over-thicken the soup), then simmered gently in the broth until the rice swells and absorbs the surrounding liquid. The result should be rice grains that are distinct, slightly swollen, and tender — surrounded by a light, flavourful broth that carries all the accumulated umami from the nabe. An egg beaten and drizzled into the simmering zōsui creates a silken egg-ribbon effect (tamago-toji). Garnishes include sliced green onion, mitsuba, and crumbled nori. Zōsui is the meal's natural ending point when sharing nabe — the entire table participates in deciding when to transition from the nabe to the zōsui, and the host prepares it at the table in the same donabe or nabe pot.

Clean, concentrated broth from the nabe surrounding swollen, tender rice grains; egg ribbons add richness and protein; the flavour is the accumulated umami of the entire meal's cooking — a distillation of what came before