How to Make Yakiimo(Slow Roasted Japanese Sweet Potatoes)

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Yakiimo is a 1-ingredient simple snack made by just roasting sweet potatoes. Slow-roasted sweet potatoes become so sweet without adding any sugar, making them the perfect healthy snack with vitamins and fiber.

Yakiimo made with Japanese sweet potato nreak in half and placed on a table

What is Yakiimo?

“Yakiimo”, or “Yaki Imo” is a Japanese word meaning roasted sweet potato. “Yaki” means roasting and “Imo” means potatoes in general. Its meaning seems simple but its meaning is very specific. Yakiimo is Japanese sweet potatoes slowly roasted to maximize its sweetness.

If you’ve ever been to Japan, you’ll know that Yakiimo is widely available everywhere. A lot of grocery stores sell house-roasted Yakiimo and people wait in line to get some freshly roasted sweet potatoes. There are also food trucks in Japan that specialize in Yakiimo. They slowly go around neighborhoods, attracting people who come out of their homes to get some. When I was a child, I loved the Yakiimo truck and buying some hot Yakiimo for a snack!

Yakiimo is not only sweet and delicious, but they’re also nutritious too! They are packed with vitamins and fiber and relatively low fat. It is famous that K-pop idols eat sweet potatoes when they try to lose some weight. Roasted sweet potatoes are healthy and nourishing!

Freshly baked sweet potatoes peeking from the aluminum foil.

Which sweet potatoes to choose

Most traditional ones, especially those found in Japan, are made with only Japanese sweet potatoes. But you can use other varieties too! The outcome is somewhat different, but they are all so delicious in their each way.

Japanese Sweet Potatoes – Slow-roasted sweet Japanese sweet potatoes are so sweet and tender, but firm enough to bite into delicious flesh.

Regular Sweet Potatoes – Regular aka orange sweet potatoes are the ones that are widely available in most of the grocery stores in the US. Their flesh is more moist and tender than Japanese sweet potatoes. They are so soft that you can scoop the flesh with a spoon like creamy pudding, perfect for an easy dessert. They release more juice while baking, so I recommend lining a baking pan to prevent burning on the pan and for easy cleanup.

Scooping soft and juicy flesh from yakiimo with a spoon.

Purple Sweet Potatoes – While orange sweet potatoes are rich in beta-carotene, purple ones are rich in anthocyanins. The texture is close to Japanese sweet potatoes. Great choice if you want bright purple yakiimo.

How to make Slow-Roasted Japanese Sweet Potatoes

First of all, let’s start with cleaning the sweet potatoes. Use a vegetable brush or hands to scrub the sweet potatoes well under running water.

Piece some holes with a fork. Sweet potatoes can explode in the oven if you don’t piece holes or cut them, as heated air can’t vent from the sweet potato while cooking. Even though I have never experienced the explosion myself even when I forget to pierce some holes, I recommend doing so to avoid any potential danger.

Then, wrap the potatoes individually in aluminum foil while the potatoes are still wet. Arrange them on a baking sheet in a single layer. Bake in the cold oven set to 325°F. No need to preheat the oven beforehand. Slow cooking is the key to the sweetest Yakiimo, so we’re starting with cold and gradually cooking them.

Sweet potatoes are wrapped in aluminum foil on a baking sheet.

Cook until the potatoes are tender. The cooking time depends on factors such as the size, number, and how crowded they are in the baking sheet. For medium-sized potatoes, aim for about 90 minutes of cooking time. For the small potatoes, test the tenderness at 1 hour. For bigger potatoes, cook them longer.

To test the tenderness, pierce a fork into the potatoes. If the fork sinks into the sweet potato smoothly, it’s ready! Let them cool and enjoy!

How to eat Yakiimo

While freshly baked Yakiimo is amazing, there are other ways to enjoy them.

Cold Yakiimo is as enjoyable as warm.

Adding toppings is also fun! Add butter to warm Yakiimo and drizzle over maple syrup or honey as you would do with pancakes. Add Jamm nuts, seeds, and fruits, the possibilities are endless!

I enjoyed mine with tahini, almond slices, and cinnamon over orange sweet potato Yakiimo. Be creative and find your favorite combo!

Slow roasted regular (orange) sweet potato is cut in half and topped with tahini and almond slices.

Frequently Asked Questions

Can you freeze roasted sweet potatoes?

Yes, absolutely! Cut them into individual servings, wrap them individually in cling wrap, and store in an airtight container in the freezer. Enjoy within 3 weeks. To enjoy them, remove them from the freezer and let sit to defrost for 10-15 minutes. Half-frozen Yakiimo tastes like ice cream. Or microwave or cook in the oven to reheat.

Slow roasted Japanese sweet potatoes on a plate.

Love sweet potatoes? Try this!

Sweet Potato Truffles

Sweet Potato Oat Cookies with Marshmallows

Sweet Potato Peanut Stew with Cauliflower and Kale

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