DAIGAKU IMO (College Sweet Potatoes) are available in any Japanese deli. In the 1920s, Tokyo Daigaku university students sold these to make their tuition (there are a couple of other rumors how it was named, but none denying deliciousness). Usually sweet potatoes are deep fried, then coated with a heavy sugar syrup = lots of calories. I reduced the oil, eliminated the sugar, but added a little butter because I like it with my maple syrup.
Look for the red-skinned variety of sweet potatoes (pictured in next photo). Traditionally sprinkled with black sesame seeds (didn't have for photo) but a combination of sesame seeds is pretty too. —BoulderGalinTokyo
4 (but most likely 2)
grams Japanese Sweet Potato (about 2) with red skins
Wash sweet potatoes with a vegetable brush (you may peel if you like).
Cut in half the long way, then cut into chunks.
Microwave on High for about 3 to 5 minutes depending on the width of your potatoes (mine were about 1 1/2 inch diameter, 3 min. was fine).
In skillet, heat oil to medium hot, add the sweet potatoes and butter and stir once so all sides of potatoes are coated with the oil. Cook until one side is done, then turn potatoes over (be careful not to break apart).
When sweet potatoes look like they've been deep fried, remove from the skillet and place sweet potatoes on a plate in a single layer.
Remove oil from the skillet. Add the maple syrup. Cook, stirring constantly until it thickens enough that the syrup coats a spoon and slowly drops into pan. Pour the maple syrup over the sweet potatoes to coat completely. Cool.
Sprinkle with sesame seeds. Cool until the maple syrup hardens.
Vegan: Eliminate butter in step 4. Instead add a couple drops of soy sauce to step 6. Not too much or the potatoes will look dark. Or use 'white' soy sauce.