Japanese Sweet Potato Cakes

It's fall harvest season in Japan.


We've been eating persimmons, chestnuts, apples, and of course, sweet potatoes.


We could eat these all day long. Field trips in the fall to harvest sweet potatoes (oimo hori) are a common activity in kindergarten, and I still remember our children getting on a bus, and coming back hours later, covered in dirt and proudly carrying their bags full of sweet potatoes fresh from the earth. I miss apple picking back home in New England terribly – it's something we did every fall with the boys before we moved here – but I am so glad they get to have this sort of experience while living here.

One spring, they even got to plant sweet potatoes at our homestay family in Gifu-ken, and they have also planted them on the garden in their kindergarten, along with many other vegetables.

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The other day our homestay family sent us a wonderful package of freshly harvested sweet potatoes and chestnuts and lotus root. Plain, roasted sweet potato, or yaki imo, is the best. It is less sweet than the sweet potatoes, or yams, I grew up with. It's a beautiful golden color (you can also get purple ones these days) and the taste is reminiscent of chestnut. You can roast it at home in an oven at 400 degrees for a wonderful plain after-school snack, or, if you live here, you can purchase it from the "yaki imo" vendor who makes his rounds in the neighborhood in the fall.  I will never forget lying with my newborn daughter the day she was born and hearing the distinctive sound of the potato man in our neighborhood. Such a Japanese fall sound for me, forever linked now with the lovely memory of a peaceful birth.

In addition to plain roasted sweet potato, I like to cook it in a vegetable braise, dice it and roast it with olive oil and herbs, make caramelized sweet potato (daigaku imo), and bake sweet potato cakes. Sweet potato cakes are a wonderful way to enhance the sweetness without going overboard. Here's a photo. A recipe follows, and I'll try to post a recipe for daigaku imo too sometime in the next few days.


Japanese Sweet Potato Cakes

Sweet potatoes, about 2 medium or 400 grams 

40 grams butter (about 2-3 tablespoons), softened

70 grams sugar (about 1/3 of a cup)

One egg yolk

2 T cream


For flavoring – a splash of rum, or a generous teaspoon of vanilla essence, or cinnamon. We love vanilla.

One more egg yolk for brushing on top of the cakes before baking.

*Note: All measurements are approximate and leave much room for flexibility! I'm not much of a measurer. A few potatoes, a dollop of butter, a splash of cream – this is how I bake these and it turns out fine. These are more forgiving than other baked goods. So don't worry about this part too much and definitely don't feel you need to race out to buy a cooking scale! I happen to own one because Japanese recipes call for them. 


Roast your sweet potatoes in the oven until they are soft, then cut in half and scoop out the insides into a bowl. If you mix in the butter right away there is no need to wait for it to soften, as the heat of the potatoes will do it for you. Mix in the egg yolk, cream, sugar, and flavoring of your choice, and mash all together with a wooden spoon until creamy. Kids love doing this part! Now add enough flour to bind it all together so that you can mold it without it losing its shape. Add flour only a little at a time, because you want the dough to remain creamy and soft. Some recipes don't even call for any flour at all but I think it is helpful. I probably added about 1/2 a cup in the end altogether.

Put your cakes on a greased cookie sheet (I usually use parchment paper instead of grease) and then brush the tops with egg yolk. Pop them in the oven at 350 for about 15-20 minutes, and enjoy! 


If you can't get Japanese sweet potato where you live, perhaps this would be good with butternut squash, pumpkin, or yams. 

What are your favorite ways to cook with fall harvest vegetables and fruits? I'd love to hear. 


11 thoughts on “Japanese Sweet Potato Cakes

  1. Christine - Origami Mommy

    When my husband and I were students (years and years ago!) we participated in a program where we each lived with a Japanese family for a summer. Both of us were placed with families in a small town in the countryside, and in fact, that’s where we first met each other. These days when we visit that town we usually stay with the family which hosted my husband, because they also run a little inn so they have enough room for us and our children. Many families in that area grow their own vegetables and/or rice.

  2. tessa

    The sweet potato cakes look so good- and easy! thank you. I’ve been eating baked yams for an afternoon snack. I used to make baked apples a lot-brown sugar, butter, cinnamon in the apple and some water in the baking dish- nothing fancy but nice to be reminded. I miss New York apples though (sorry California!). I miss that east coast apple picking too. The cider making and old fashioned doughnuts… Another nice autumn treat is to make a recipe for pumpkin pie but bake it (adjust the time!) in individual little ramekins rather than a pie shell. This bakes much faster than a pumpkin pie – nice!

  3. Ellen

    These look very yummy. I love sweet potatoes – my children, well…not so much, but they might like them this way. Believe it or not, I’ve never tried a persimmon. Do you eat it raw like other fruit & vegetables? Do you cook it?


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