Japan (Nagasaki Chinese-influenced origin; nationwide adoption; Okinawa rafute is a related variant with awamori)
Kakuni (角煮, 'square simmered') is the Japanese approach to braised pork belly — thick blocks of pork belly (3–4cm cubes) simmered for 2–3 hours in sake, soy sauce, mirin, and sugar until the collagen converts to gelatin, the fat becomes translucent and tender, and the whole block trembles with a yielding richness that has become one of the defining textures of Japanese comfort food. The name refers to the characteristic square cut. The method requires initial par-boiling to remove impurities (for 10 minutes with leek and ginger), a rest period, then a long simmer in the braising liquid. Ideally, kakuni is made a day ahead and chilled — the congealed fat layer is removed, and the pork reheated in the reduced sauce which, by then, has achieved a concentrated sweet-soy glaze quality. Simmering in a liquid that starts with sake and mirin burned off before soy is added prevents the harsh alcohol edge that raw sake addition can impart. Nagasaki's Buta no Kakuni (with Chinese-influenced ryukyu-style) uses rice wine, a technique imported from Chinese braised pork traditions, while Tokyo-style uses standard sake and domestic soy. Served with hard-boiled eggs simmered in the same liquid (umani tamago) and blanched spinach with sesame.
Sweet, soy-caramelised, richly gelatinous pork with trembling fat; deep mirin sweetness; concentrated glaze coats each cube; pairs with white rice and mustard
{"Initial par-boil 10 minutes with leek and ginger: removes impurities and off-odours before braising","Burn off sake and mirin before adding soy — prevents harsh alcohol note in finished dish","3-hour minimum simmer at barely-simmering temperature — rolling boil makes tough","Chill overnight: remove solidified surface fat; flavours deepen; reheating concentrates glaze","Otoshibuta (drop lid) essential for even cooking without total submersion in liquid"}
{"Baking paper as makeshift otoshibuta: cut to fit the pot interior and rest directly on liquid surface","Add a small amount of rice vinegar to the braising liquid — tenderises collagen faster and balances sweetness","Pressure cooker shortcut: 25–30 minutes at full pressure achieves similar collagen conversion as 3-hour simmer","Kakuni sandwich (nikuman adaptation): slice chilled kakuni thin, place in steamed bao bun with pickled mustard greens"}
{"Skipping the par-boil step — impurities and off-flavours remain in the final braising liquid","Boiling rather than barely simmering — collagen converts but meat becomes fibrous rather than silky","Not resting overnight — day-of kakuni lacks the concentrated glaze and depth of next-day version","Adding soy from the start without burning alcohol first — harsh alcohol edge persists"}
Japanese Cooking: A Simple Art — Shizuo Tsuji; The Japanese Kitchen — Hiroko Shimbo