Cooked in the ground

Jigoku-mushi — the one to do

Jigoku-mushi is steaming food directly in a geothermal vent. At Kannawa's public steam kitchen you buy raw ingredients — prawns, corn, sweet potato, eggs, whole vegetables, sometimes chicken — put them in a woven basket, and lower them into a stone chamber.

Ten to twenty minutes depending on what you chose. The steam is slightly salty and mineral, so it seasons as it cooks and the food needs almost nothing added. Local households have cooked this way for centuries and some Kannawa kitchens still have their own steam box.

A steamed egg out of a Beppu vent tastes different from a boiled egg. That is not romance — it is dissolved minerals in the steam.

Toriten — chicken, but tempura

Toriten is chicken marinated in soy, ginger and garlic, then fried in a tempura batter and served with ponzu and mustard. It is not karaage — the batter is light and the marinade is the point — and it belongs to Oita specifically.

It is on every ordinary menu in the prefecture, it costs very little, and it is the single most reliable thing to order if you want to eat what people here actually eat.

Reimen — cold noodles, cold broth

Beppu reimen was created around 1950 by a cook who had come back from Manchuria. The noodles are thick and chewy, made of wheat, buckwheat and starch. They come in a cold, Japanese-style seafood broth, topped with cabbage kimchi.

There is a warm version too, called onmen. Ask for either and watch a Beppu person approve of you.

And the fish, which is very good and gets no attention

The straits north of here produce seki-aji and seki-saba — horse mackerel and mackerel caught in fierce tidal currents off Saganoseki, line-caught one at a time and handled so carefully that they are among the most expensive fish of their kind in Japan.

Mackerel is normally cooked, because it spoils fast. Seki-saba is served raw, and that is the entire point of it.