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Focus Global Kitchen

A Guide to Tokyo’s Sweet Potato Heaven

Ana Vigueras-LaRochelle April 11, 2020

Image source: Japanese Cooking 101

More valuable than you thought

I ran about 12 miles one Sunday in February to the Shinagawa Yakiimo Terrace to join crowds of people like me: Yakiimo Otaku. At Tokyo’s annual Yakiimo festival, Japanese sweet potato lovers stand in line for 30 freezing minutes or more, in 20 degree weather (3°C) to purchase roasted sweet potatoes and sweet potato-inspired cakes, pies, drinks, and more. I wanted to try my first Okinawan sweet potato, known for its enticingly purple flesh. But for more than the potato itself, I ran all that way to create a kind of small pilgrimage so I could identify as a true Sweet Potato lover, or Yakiimo Otaku.

Definition of Otaku: A person with an obsessive interest in a particular aspect of popular culture, sometimes to the detriment of their functioning in society.

Definition of a Yakiimo Otaku: Someone who loves Yakiimo and proactively seeks out ways to incorporate yakiimo into their life.

First Experience 

For those who have never had a yakiimo, I want to try to describe the experience. Anticipation is painful because from many grocery stores in Tokyo, you can smell the aroma of the sweet potato from outside the store. The aroma can be described as a mix of charred marshmallow and something salty balanced together. As you approach the store, you can see a corner of warm yellow light hiding brown crinkly bags. The brown bags quietly quiver as I lift the plastic door shielding them from the winter air. I gently handle each bag, judging the size of each mass. I don’t want one too big but they are all massive potatoes, weighing in at maybe 300 grams each, roughly the size of two baseballs. Finally I pick, usually one with the side oozing out a caramel like goo, but I think this is a natural effect of being baked in such high heat on a bed of rocks. I cradle the potato in my palm, still wrapped in its bag, gently squeezing it to see if it is only slightly firm. The easier it is to squish, the more delicious it will taste.

And that’s it. I pay, and then contrary to the custom of eating the potato by using the bag to cover the sticky skin, I like to take my potato out of its bag, admire the naked purple skin and crack it like a croissant. I take a look at the inside, it’s very yellow, not orange like the ones in the United States, and I take a bite with the skin still on. The taste is shockingly sweet but it’s completely due to the potato’s natural chemistry. No sweeteners are added into the spud. Sweet, musky, creamy. It goes well with milk and sometimes I will indulge and get the incredibly delicious and high fat, Japanese milk that is available at all convenience stores. The taste is comparable to a banana marshmallow boat (banana stuffed with chocolate then wrapped in tin foil and baked on an outdoor fire). That’s the closest American equivalent to the taste of a yakiimo. But while that banana and chocolate will spike your sugar levels, the sweet potato is mainly starch, completely natural, and will do a better job at keeping you full and energized. Regardless, it is painfully delicious. Close your eyes and nod, delicious.

Unfortunately, I don’t remember the first time I had a Japanese roasted sweet potato, the yakiimo. The first experience blends in with the roughly 200 yakiimo I have had in Japan so far. I love yakiimo so much that I try to have one every day, and I feel a little lost without it—while some people feel like a meal is not complete without rice or bread, my day isn’t complete if I don’t have at least one yakiimo. Some days I wish that yakiimo was the perfect food, and the only thing that would make it be that way is if it had a little bit more protein and fat. Yakiimo is filled with incredible vitamins and minerals, and saved the Japanese from famine in the mid-1700s.

What’s so Great About Snacking or Making a Meal out of Sweet Potatoes? 

What’s so special about an oven-baked sweet potato? The name seems ordinary enough—yaki means grilled, cooking, or frying and imo means potato.

But maybe it’s in the baking method. The ovens used aren’t just electricity-powered ovens that one bakes a frozen pizza or Aunt Jemima cake in. Instead, these are usually cast iron ovens with a bed of hot rocks as a heating element (see photo). Baking at a high heat and wrapping the potato in aluminum foil allows for the potato to become very moist and the outside to be crispy. Baking in less powerful heat produces dry yakiimo.

Another unique aspect of Japanese sweet potato is the diversity of flavors. These are not ordinary sweet potatoes that we can find in any store in Philadelphia for a dollar per pound. There are a variety of Japanese sweet potatoes and the following are some of the most popular: 

  • Haruka Beni: The sweetest variety and most often found at super markets
  • Halloween Sweet: Surprisingly described as containing a pumpkin flavor, kabocha, in Japanese and also a shocking orange. 
  • Naruto Kintoki Sato Musume: Grown in sandy soil from Tokushima. 
  • Ninjin Imo: Carroty taste.
  • Murasaki: Okinawan delicacy, purple potato (see photo above)

I tried the murasaki at the Yakiimo Festival. I’ve heard it’s good for people who are not used to eating yakiimo because it is not as sweet as a Haruka Beni. It takes like a mix between a banana, plantain, and potato, but also has a musky sweetness to it. This potato is known to grow in Okinawa, southern Japan, but why the purple color? 

The accessibility of the yakiimo is another amazing thing about the healthy snack; it is available almost anywhere in Tokyo. It is also cheap: about 200 yen (less than two dollars) for one potato.  Sometimes, in residential areas of Tokyo, you will hear the Yaki-Imo Truck blaring a pre-recorded male voice urging you to indulge in the imo. I’ve never had one from the truck, but that’s my next goal as a yakiimo lover. The price of sweet potatoes from the truck are around 300 to 500 yen, but are said to taste amazing and are fixtures of Tokyoites’ childhoods.

A Brief History Lesson

Today, picking and eating yakiimo is a mark of fall and winter, similar to how going apple picking in the United States signifies the coming fall. They’re warm and filling, and can also be considered a comfort food. However, in Japanese history, yakiimo have also been life-saving.

The potato and sweet potato originated from South America and traveled to Japan during the flourishing 15th-century trade routes between Europe and much of East and South Asia, including the Philippines, China and Japan. Potatoes were brought to southern Japan first, where they first were found in Okinawa. At this point, Okinawa was not a part of Japan but after the Invasion of Ryukyu (Okinawa), the Shogun saw value in the sweet potato. Additionally, in the Kyoho period, a famine lasting from 1732 to 1733 occured in the southern island of today’s Kyushu when an overreliance on wheat and barley left populations vulnerable. The grain crop was destroyed by harsh climate and the rotting of seedlings resulted in high rice prices of rice and buckwheat. After this when more than 12,000 people perished from starvation, the Shogun promoted diverse cultivation of crops, particularly high energy crops like the sweet potato. The sweet potato, known as the satsuma imo, first started to become widely consumed in Kagoshima, Japan and its nutritional value was promoted by the Confucian scholar and teacher Aoki Konyo, known as the Potato Doctor. Since this time of trade and nutritional information sharing, the sweet potato became one of the most widely adopted crops because of its resilient nature and ability to grow in poor soil, among other reasons (including it’s delicious versatility).

It’s important to include this information because the sweet potato is seen as a remarkable vegetable that saves lives and the Japanese do not forget these ideas. I think, as food shortages continue to grow around the world, the sweet potato has potential to feed these populations. Similar to how the peanut became a form of sustenance for undernourished kids in its processed form of Plumpy’nut, a processed form of the sweet potato might also serve such a purpose if we can further control its nutritional value and develop a well-rounded product with macronutrients. I heard about the sweet potato from the book The Blue Zones: Lessons for Living Longer from the People Who’ve Lived the Longest by Dan Buettner, an explorer and National Geographic Fellow, in which Buettner discusses several accounts of centenarians attributing their long lives to eating yakiimo daily. There’s a lot of potential.

 

Other than the Yakiimo Festival where can people get premium yakiimo 

Some stores and stands in Tokyo where I recommend you to find Yakiimo of various types:

Fuji in Gotokoji:
I was looking for a store where I could get gourmet yaki imo when the Yaki imo festival was not in town. Fuji is actually a 15 minute bike ride from Temple Japan Campus and around the Shinto Temple, Gotokuji, that is famous for the thousands of maneki neko cat figurines on display.

The best Yakiimo: Maruetsu Petit in Chiyoda, Ku
Alright some yakiimo have more potato tastes and some are overly sweet but I think that the Maruetsu Petit in Awajicho, Tokyo has the best yakiimo. They are large and the correct ratio of sweet. To me that means they never taste like a potato but instead have that indescribable prime yakiimo flavor.

Cheapest Yakiimo: Lawson 100 Yen Stores 

Literally 100 yen for one yakiimo. 

The machines used to bake the potatoes are smaller so I don’t think that the potatoes come out as well cooked as some other grocery stores, but if it’s 2 am and you want a yakiimo this is your only option!

Worst Yakiimo: Rotten Ones 

I highly advise staying away from rotten yakiimo. The only way this can happen is if you buy your own sweet potato, forget to notice the tips are turning green and soggy, then bake it in the microwave. The taste is skin-crawlingly horrendous, it’s hard to describe because of the huge physical shock I get after eating it. Goose bump disgusting.

Why I hope you try this potato in Japan

The Japanese sweet potato plays a large role in Japanese popular culture. You see characters in anime and manga eating the food, and there was even a Doraemon episode where the entire town turned into sweet potatoes. As I mentioned before, many sweets are made from the potato and if you can’t find the potato in its raw form, there is without a doubt a sweet potato confectionary nearby. I think foreigners are sometimes hesitant to reach into a potato cart because we don’t want to start grabbing at things we shouldn’t be, but I hope that this small guide allows you to become aware of this delicious, but often unnoticed and underrated, Japanese food. So, do not be afraid to try it for yourself. 

(Different ways you will see the potato displayed)