Chashu is the reason a bowl of ramen smells like a decision. The name is borrowed from Cantonese char siu, the lacquered roast pork hanging in siu mei windows, but the Japanese ramen version is a different animal cooked a different way, rolled, tied and braised instead of roasted, and its by-products season half the menu. Here is how the thing is built, in the shop and in a home kitchen, because it is one of the few professional ramen components that transfers to a stove intact.
The cut and the roll
Pork belly is the classical cut, layered fat and meat in equal conversation, cut as a wide slab and rolled into a tight log with butcher's string at intervals. The roll does two jobs: it makes a cylinder that slices into neat discs, and it forces the fat layers to run in a spiral, so every slice carries fat and lean in proportion instead of one end being all lard. A shoulder roll is the lean alternative, firmer and cleaner, better for slicing thin and holding shape. Skin on or off is a house decision, and both camps are stubborn.
The braise
The liquid is soy sauce, sake, mirin and sugar, with water or stock to give it depth, plus the aromatics, garlic, ginger, spring onion, sometimes the white part of leek. The log sears first in a hot pot to build a browned shell, then the liquid goes in, comes to the barest simmer, and the lid goes down for two to three hours, the pot at a temperature where the collagen melts and the meat holds. What you are waiting for is the state where a chopstick meets no resistance, the fat has turned translucent and the whole log reads as tender rather than cooked. Cool it in its own liquid, overnight if you can, because the cooling log drinks seasoning back in as it rests, and cold chashu slices clean while warm chashu smears.
The braise is the kitchen
Nothing that touched the pork gets thrown away. The braising liquid, now a pork-scented tare, thins into soup seasoning, becomes the marinade for ramen eggs, the subject of its own piece on this site, and reduces into a glaze for the seared slices. In a ramen shop the chashu pot is the second stock pot, and the bowls are seasoned with the memory of the pork before the pork itself arrives on top. Some shops finish slices under a blowtorch or on a grill to order, the charred edge against the silk, and it is worth trying at home with a hot pan, thirty seconds a side.
Serving, ours and yours
Slice the log into discs a few millimetres thick, across the string, and lay them over the bowl with the fat edge in the soup, where it melts a little gloss into the surface. Our Char Siew Ramen carries four slices over the Kyushu pork bone base, and the same chashu tops the Miso, the Kyushu, the Tsukimi and the Beppu Ramen. If you braise your own at home, the honest test is the slice that disappears from the cutting board before it reaches the bowl. The kitchen will not judge. We understand the impulse.