Nagasaki, Japan — adapted from Chinese dongpo rou via Nagasaki trade routes in the Edo period; now a national Japanese specialty with regional variations
Kakuni (square-braised, from 'kaku' — square/cube and 'ni' — simmered) is one of Japan's most celebrated pork preparations — large cubes of pork belly (sometimes the whole belly cut into thick slabs) braised for hours in a sweet-soy liquid until the fat renders to trembling softness and the skin achieves a glossy, caramelised exterior. The technique is Japanese in execution but has direct Chinese origins — dongpo rou (Red-braised pork belly from Hangzhou, associated with the Song dynasty poet Su Dongpo) uses an identical preparation logic, and kakuni arrived in Japan through trade contact with China via Nagasaki, where it is still considered a Nagasaki specialty. The Japanese version is typically sweeter and uses more mirin, while the Chinese version varies by region. The kakuni process involves a preliminary step that many home cooks skip but that professionals consider essential: blanching the pork belly in boiling water with sake and ginger to remove impurities and blood, then discarding the water and starting fresh. The fresh braise uses dashi, sake, mirin, and soy in specific proportions, with rock sugar or regular sugar for the caramelising sweetness. The long cooking time (3–4 hours minimum, up to 8 hours for the finest texture) at a very low temperature allows the collagen to completely convert to gelatin while the muscle fibres remain intact — producing the characteristic 'melts and yields simultaneously' texture that defines great kakuni.
Perfect kakuni is an extraordinary combination of textures and flavours — the trembling, gelatinous fat layer, the tender but intact muscle beneath, the glossy-sweet caramelised exterior from the soy-mirin braise, and the deeply umami, sweet-savoury braising liquid as a sauce.
Blanching and fresh-start braise removes impurities that would cloud the braising liquid and create off-flavours. Long, low-temperature cooking (below 90°C) is the technique — higher temperatures convert the collagen faster but create dryer, tougher muscle fibres. The liquid level should barely cover the pork — using less liquid creates more concentrated braising and better caramelisation of the exposed surfaces. Weighing down the pork with an otoshibuta (drop lid) or similar weight keeps it submerged and ensures even braising.
Two-stage technique for maximum quality: braise the blanched pork belly whole for 3–4 hours, refrigerate overnight (the fat solidifies and can be skimmed), then cut into cubes and return to the defatted, reduced braising liquid for a final 1-hour caramelising braise. This technique produces dramatically cleaner flavour and allows fat management impossible in a single-braise approach. The removed fat is excellent for seasoning vegetables or frying rice. Serve kakuni with karashi (Japanese mustard) and finely cut green onion — the mustard cuts the fat's richness; the onion provides fresh aromatics.
Rushing the cooking time — kakuni cannot be adequately prepared in under 3 hours; the collagen conversion requires time. Boiling rather than gently simmering — vigorous boiling toughens the muscle fibres before the collagen converts. Insufficient initial sweetness in the braising liquid — the liquid must be significantly sweeter than the desired final flavour because it concentrates during cooking.
The Japanese Culinary Academy's Complete Japanese Cuisine Series