What sits on top is called abura-kasu. Beef offal, deep-fried until the fat has rendered out of it and gone, leaving something dry and dense and dark. It is chopped small and scattered over the noodles.

Because the fat has already been driven off, it is chewy rather than rich, and the flavour arrives late rather than at once. Left sitting in the bowl it begins to give itself up to the broth, so a clear soup that started pale is cloudy and considerably stronger by the time you get to the bottom of it. The dish changes while you eat it, which is not true of most noodles.

This belongs to the southern part of Osaka prefecture — Matsubara, Habikino, Kashiwara and the towns around them. For most of its history it was not a speciality anybody travelled for. It was what people in those towns ate, made from a part of the animal that had to be used somehow.

It only started appearing in central Osaka, and then further afield, in the 2000s, when chains built around it multiplied quickly. Something confined to a few towns for generations became, in about twenty years, a name recognised across western Japan. Very little about the dish itself changed in the process.