TOKYO >> Sweet potatoes are considered a delicacy in Japan in the fall and winter, when they are commonly served fresh-baked and piping hot.

But the chilled version of a baked sweet potato has gained popularity as a cool summer treat.

Last month, a banner reading “Chilled baked sweet potatoes, cold, sweet and delicious!” fluttered in the breeze outside the sweet potato shop oimo lab. in Tokyo’s Koto ward.

The shop sells a variety called silk sweet, characterized by its moistness and elegant sweetness.

After the potatoes come out of the oven, they sit overnight to bring out their natural sweetness, then are frozen.

Since the shop opened in 2018, the popular chilled treat has been offered during summer.

“It has a concentrated flavor and a smooth mouthfeel,” said shop manager Koji Shimura. “It tastes like ice cream right out of the freezer. It is popular … with a wide range of people.”

Other chilled baked sweet potatoes are available in various stores. Tokyo-based fruit importer Farmind Corp. sells individually packaged Hiyashi Amaimo (“cold sweet potatoes”) that are kept refrigerated.

“It’s perfect for breakfast or as a snack,” said a Farmind spokesperson. “It’s rich in fiber and popular among women for its beauty- enhancing properties and health benefits.”

FamilyMart Co. began selling its own version of the chilled potatoes in 2017; this season, it began selling the product in early May in limited quantities and quickly sold out by early June.

Kazunori Taguchi, a senior researcher at the National Agriculture and Food Research Organization, said previous varieties of sweet potatoes were often dry; however, in recent years new varieties have delivered a much improved product.

The Beniharuka, for instance, has a high sugar content and is sticky with a moist texture. It doesn’t become too firm when chilled and is enjoyable cold, Taguchi said.