With a crisp sesame candy coating and a tender, fluffy interior, this Daigaku Imo (大学芋) is an easy Japanese sweet potato recipe that makes for a delicious afternoon snack or sweet side dish for a Japanese meal.
Trim the ends off of the sweet potato and cut it rangiri by cutting off a chunk of potato at a 45-degree angle from one end and then turning the potato 90 degrees and cutting another chunk off at a 45-degree angle. Repeat until you've cut all of the potatoes into pieces that are roughly the same size and thickness.
Soak the cut potatoes in cold water to keep them from oxidizing.
Preheat a pot with 2-inches of vegetable oil to 340 degrees F or 180 C.
Rinse and drain the potatoes and then put them in a frying pan along with the 1/4 cup of water. Cover with a lid and steam over medium-high heat until there is almost no water remaining.
Open the lid, let any remaining water burn off, and then transfer the sweet potatoes into the hot oil.
Fry these until they're golden brown (about 5 minutes), turning them over regularly to ensure they brown evenly.
When the sweet potatoes are almost done frying, add the rice syrup and sugar to the pan you steamed the potatoes in and start heating the mixture to dissolve the sugar.
Transfer the sweet potatoes directly from the oil into the glaze and toss them around in the syrup to coat them evenly. If the mixture has gotten too sticky to glaze, you can add a spoonful of water to loosen it up. Add the sesame seeds and toss to distribute evenly.