Cut the sweet potatoes including the skin diagonally into 1cm slices, or cut into thin round slices. Next cut them into 1cm pieces (as seen in the photo), then soak in water to remove the bitterness.
Soak for about 10 minutes. Strain the water but leave the potatoes slightly damp. Transfer to a plate, cover with plastic wrap, and microwave for about 3 minutes at 500 W.
Heat a pan, melt the butter, then fry the sweet potatoes with salt and pepper.
Finally, coat with the sugar, fry some more, and you're done.
Story Behind this Recipe
I wanted to use sweet potatoes as a bento dish, so I cut them into small pieces to fit in the bento box, and fried with butter.
When you microwave the sweet potatoes, don't cook them too long. They will become too soft and break. It's better to leave them a little undercooked, even if they are still a bit hard.