-
1
Place the pork belly cubes in a large pot and cover generously with cold water. Bring to a rolling boil, then drain and rinse each cube under cold running water, removing all grey foam and surface proteins. The rinsed cubes should be clean and white — no residue on the flesh or skin.
-
2
Return the blanched pork to a clean pot. Add the dashi, sake, mirin, and soy sauce. Bring slowly to a bare simmer — 90–95°C, never a rolling boil. A surface tremor and occasional lazy bubble is correct; sustained high heat is not. Hold at this temperature for a minimum of two hours, skimming any further foam as it rises.
-
3
This is where the dish is decided. At the two-hour mark, gently jostle the pot: the cubes must wobble — trembling and yielding rather than holding their shape — indicating full collagen conversion. If they hold firm, continue at the same low temperature, checking every thirty minutes. A cube that does not wobble will not lacquer correctly and will resist the final reduction.
-
4
Remove the pork and set aside. Increase the heat to a moderate simmer and reduce the braising liquid in stages: reduce by one-third, taste, add reserved dashi if concentration becomes too saline, reduce again. Continue until the sauce coats a spoon and falls in slow, honey-weight drops. Returned to the pot, the pork should be lacquered — a deep mahogany gloss on every surface.
-
5
Return the pork cubes to the reduced sauce and roll gently to coat. The skin should appear gelatinised and transparent; the sauce should cling rather than pool. Serve immediately, or cool and refrigerate overnight — solidified surface fat is removed cold before gentle reheating in the sauce. Accompany with karashi mustard at table.