According to Katsuyasu Ito, chef and owner of L’Aureole Tanohata, Hidemitsu Kikuchi, is the last person producing imo no kona (potato flour) commercially in Japan.

Working in Tanohata, a tiny village on the Sanriku coast of northeastern Iwate Prefecture, Kikuchi should be heartily applauded for his steadfast work each year to create this local food, which is traditionally made into little dango dumplings or manjū steamed buns. The process to craft this product is both laborious and time-consuming, but the possibilities for the naturally silky and gluten-free flour are endless.

Although a few additional varieties of potatoes are slowly making their way to Japan, the majority of potatoes grown here are either of the May Queen or Danshaku varieties. May Queen are slightly creamy, thin-skinned and oval, while Danshaku are round, a bit starchy and develop a thick skin. Due to their oval shape, which helps Kikuchi thread the potatoes on a string; and their lack of eyes, which speeds up the peeling process, May Queen potatoes are favored over Danshaku for producing potato flour.

In January, shortly after the beginning of the new year, Kikuchi, assisted by his mother, Fuchi, hauls the summer harvest of May Queen potatoes out of storage and lays them out in the cold Iwate winter air to freeze for two to three days: the first freezing in what will be multiple cycles of freezing and thawing over the course of the following two months.

Once frozen, he and his mother bring the potatoes inside to peel, rubbing and scraping the peels off using their bare fingernails, as the potatoes thaw. Now thawed, the once-frozen potatoes are soft enough to stab through the center with a long heavy needle. Kikuchi threads the potatoes so they butt up against each other onto long strands of thick twine. These strands are then tied together in groups of five or six and anchored onto a rope suspended over the edge of an icy stream.

The potatoes soak in the snowy water over the course of two weeks to take away their bitterness and allow tiny cavities in the porous potatoes to fill with ice water, which facilitates quick freezing when they are finally removed from the stream.

“Leave the potatoes too long in the water and they will blacken,” cautions Kikuchi.

Once the potatoes are removed from the frigid water they are hung out again in the bitter cold air to freeze once again. As the weather warms slightly, the potatoes will begin to thaw in the sun, thus dripping out accumulated moisture, then freeze again at night. This alternating sequence will eventually allow the potatoes to become completely dehydrated.

By the end of February, the potatoes will be feather-light, like balsa wood. These buoyant, off-white ovals are then packed into feed bags and kept in a cool, dry place until milled, as needed, into flour. The potatoes will keep whole until the rainy season in June, at which time they risk molding, and are then milled and stored carefully.

The process of drying these potatoes, and the surreal image of the strands submerged in the icy stream, captures me in a way that I don’t often experience. And I worry for the future of this unassuming, yet incredibly versatile, ingredient.

Thus far, I have guarded the existence of this flour, lest the limited supply be gobbled up by chefs in Tokyo, but I am ready to share this secret with the world.

Tanohata, where Kikuchi produces his potato flour, is a town of about 3,500 inhabitants and was half-destroyed by the tsunami that followed the Great East Japan Earthquake of 2011. Tanohata has an abundance of natural resources — the surrounding mountains are full of game, mushrooms, nuts and native plants while the nearby lush hills are home to an inspirational native Japanese grass-fed dairy — but is remote, and would benefit from more Japan-wide recognition to hasten its progress toward revitalization. It is my hope that if demand increases for potato flour, able-bodied Tanohata-based residents will see the potential in increasing production of this versatile ingredient.

I have recently been introducing interesting Japanese ingredients to my good pal, ex-Chez Panisse chef Jerome Waag, co-owner of the Blind Donkey in Tokyo. I tried to describe Tanohata’s flour to Jerome, but could not get past the inevitable preconception that working with potato flour creates something akin to a potato slurry. This is a truly revolutionary ingredient that looks and acts like flour in all of its good ways, but does not gum-up — and it also has a lovely flavor.

In Iwate Prefecture, chef Katsuyasu Ito of L’Aureole Tanohata, an outstanding eatery perched above a secluded cove with a breathtakingly beautiful view, has combined this homely flour with local grass-fed milk and a dab of butter and turned it into a genius bechamel sauce, which he uses as a base for a seafood and leafy greens white stew, all made with local ingredients [see sidebar].

To get to Tanohata is no small feat from most places in Japan, but the last leg of the journey involves a clickity-clack ride along the Kita-Rias Line that runs adjacent to the Sanriku coast on a picturesque vintage train fitted with wooden tables for eating your bento. For the food-obsessed, Tanohata is certainly a destination worth exploring, and potato flour an ingredient worth trying.

L’Aureole Tanohata: Aketo 309-5, Tanohata, Shimohei-gun, Iwate Prefecture, 028-8402; Tel: 080-9014-9000. Lunch 12-2 p.m. (LO), dinner 6-8 p.m. (LO).

Potato flour fish stew

• 1 liter of milk
• 3 tablespoons Iwate potato flour
• 2 tablespoons butter
• 2 teaspoons sea salt
• 500 grams white fish
• Shimeji mushrooms
• Bok choy

Simmer the potato flour and milk for about 20 minutes. Stir in the butter. Sear the white fish in olive oil, and add to the pot with a couple handfuls of shimeji mushrooms, a small head of bok choy (quartered lengthwise and blanched) and chopped delicate herbs such as chives and chervil for garnish.

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