Preparation: Cut the sweet potatoes into bite-sized pieces and place them in a bowl. Add enough water to cover the sweet potatoes and soak for five minutes.
Microwave: Drain the sweet potatoes and cover the bowl with plastic wrap. Microwave for five minutes or until the sweet potatoes are cooked. Remove any excess water from the sweet potatoes with a paper towel.
Pan-frying: Heat the oil in a frying pan over medium-high heat. Once the oil is hot, add the sweet potatoes and pan fry for five minutes or until golden brown and crispy. Transfer the fried sweet potatoes to a plate lined with paper towels to drain any excess oil.
Make Sweet Syrup: Remove the oil from the same pan, add the sugar, mirin, water, and soy sauce, and cook over low heat until it thickens, constantly stirring to prevent burning.
Combine: Add the fried sweet potatoes to the pan and stir until they are evenly coated with the sweet syrup.
Topping: Sprinkle sesame seeds on top for extra flavor.
Notes
Storage: Transfer Daigaku Imo to an airtight container and refrigerate. It will keep for 3 to 4 days.
Soak the cut pieces in water for about 5 to 10 minutes to keep the color bright and prevent discoloration.
If you prefer a crispier texture, skip microwaving and deep-fry the sweet potatoes. Cook them slowly at medium-low heat (around 160°C / 320°F) so they become tender on the inside and golden on the outside.
For a lower-oil method, use an air fryer. Air fry until they are crispy on the outside and soft on the inside. A quick spritz of oil can help them brown evenly.