When autumn arrives, one of the most beloved Japanese snacks is Daigaku Imo, or candied sweet potatoes. Crispy on the outside, fluffy on the inside, and coated with a glossy sweet sauce, this snack is simple yet full of flavor. It has long been enjoyed as a student favorite and as a popular treat at food stalls.
The name Daigaku Imo literally means “university potatoes.” In Japanese, daigaku refers to university, but in English it can sometimes be translated as “college” depending on the country. The snack is said to have become popular among university students because it was cheap, filling, and delicious—hence the name.
With just a handful of ingredients and a few tips, you can easily make Daigaku Imo at home. In this post, I’ll share the secrets to creating shiny, caramelized, and fragrant sweet potatoes just like the ones you’d find in Japan.
Ingredients
- 2 medium sweet potatoes (about 400g)
- 2 tbsp sugar
- 1 tbsp mirin
- 1 tbsp soy sauce
- Oil for frying
- A sprinkle of black sesame seeds
Instructions
- Wash the sweet potatoes well and cut them into bite-sized chunks with the skin on. Soak in water for about 10 minutes to remove excess starch, then pat dry. (This step is optional.)
- Place the sweet potatoes into a pan with cold oil. Fry over medium heat for about 5 minutes, or until a skewer goes through easily. The frying time will depend on the size of the pieces.
- In a separate small pan, combine sugar, mirin, soy sauce, and a little water. Heat over medium until the sauce thickens and becomes sticky.
- Add the fried sweet potatoes while still hot and toss them until well coated.
- Sprinkle with black sesame seeds and serve.
VIDEO: Watch How to Make It
Cooking Tips
Why Start Frying in Cold Oil? (The Secret to Sweetness)
When making Daigaku Imo (Candied Sweet Potatoes), one of the key tips is to start frying the sweet potatoes in cold oil instead of preheated oil. This might sound unusual, but here’s why it makes such a big difference:
- Even cooking inside and out
If you add sweet potatoes to already hot oil, the outside cooks too quickly and may harden before the inside becomes tender. By starting from cold oil, the temperature rises gradually, allowing the heat to penetrate evenly. The result is fluffy, soft sweet potatoes inside and a crisp outside. - Enhanced natural sweetness
Sweet potatoes contain natural starches and sugars. The slow heating process encourages the starch to break down gradually into sugars, which enhances their natural sweetness. This is why the sweet potatoes taste richer and more caramel-like when fried this way. - Less oil splatter and safer cooking
Putting wet sweet potatoes directly into hot oil often causes splattering. Starting in cold oil reduces that risk and makes the process safer, especially for home cooking. - Shorter frying time
Surprisingly, this method can actually reduce cooking time. Since the oil temperature rises along with the sweet potatoes, they reach the perfect doneness in about 5 minutes, depending on the size of the pieces.
Extra Cooking Tips for Perfect Daigaku Imo
- Cut size matters: Larger chunks take longer to fry. Keep the pieces roughly the same size so they cook evenly.
- Pat them dry well: Excess water will cause the oil to splatter and prevent crispness.
- Toss in the sauce while hot: The caramel sauce sticks best when the sweet potatoes are still warm and freshly fried.
- Eat fresh: Daigaku Imo tastes best right after cooking when the outside is glossy and the inside fluffy.
