Daigaku Imo (Japanese Candied Sweet Potatoes) 大学芋

Daigaku Imo, or Japanese Candied Sweet Potatoes, are crispy on the outside, tender inside, and coated in a glossy caramelized sugar glaze with sesame seeds. This easy Japanese snack is sweet, nutty, and irresistibly crunchy.

Japanese sweet potatoes are by far one of my favorite foods. I love them in any form, sweet or savory. I especially love them simply roasted, called yaki imo, but another way I’ve always enjoyed them is in a dessert my mom used to make called daigaku imo. When fall rolled around and they were at their peak, she’d make them for us for dessert and often served it with vanilla ice cream. She made it a few different ways—sometimes with a hard, crunchy candy coating, and other times in stick form with a syrupy glaze. The smell, the texture, and the flavors made them impossible to resist once they were served!

What is Daigaku Imo?

Daigaku Imo (大学芋), which translates to “university potatoes,” became popular in Tokyo around the early 1900s, especially among students because it was cheap, filling, and delicious. The name is said to have come from this connection, though there are a few different theories about its origin.

What makes daigaku imo so delicious is the contrast of textures—golden fried or pan-fried sweet potatoes coated in a sugar glaze that hardens into a shiny, candy-like shell. A touch of soy sauce balances the sweetness, while sesame seeds add nuttiness. In Japan, you’ll find daigaku imo sold at sweet potato specialty shops, department store food halls, and as festival snacks, especially in fall and winter when satsumaimo (Japanese sweet potatoes) are in season.

Types of Daigaku Imo: Regional Variations

Daigaku imo isn’t the same everywhere in Japan. Depending on where you are, the shape, glaze, and texture can vary:

• Kanto Region (Eastern Japan): Known for its syrupy, moist style, where sweet potatoes are cut into chunky, round, or irregular pieces and coated generously in a sticky glaze. The Beni-Azuma variety, grown in sweet-potato-famous prefectures like Ibaraki and Chiba, is especially popular for its fluffy inside and crispy outside.
• Chubu Region (Central Japan): This style leans more toward a crunchy candy shell. Instead of a gooey glaze, the sweet potatoes are coated in a thin layer of hardened sugar that gives a crisp bite, almost like brittle. This version is fun to eat because of the satisfying crunch.
• Kansai Region (Western Japan): Stick-shaped daigaku imo is common, influenced by a Chinese dish called basu. They’re often made with Naruto Kintoki sweet potatoes from Shikoku, prized for their deep golden color and natural sweetness. This style is easy to eat on the go, fitting the street-food culture of Kansai.

Each region has its own take, but they’re all delicious in their own way—whether you like syrupy, crunchy, or stick-style candied sweet potatoes!

Fried vs. Pan-Fried Daigaku Imo

The deep-fried version gives that unmistakable fried flavor and extra crispiness that holds up well against the sugar coating. It stays crunchy for longer, making it the closest to what you’d find at a specialty shop in Japan.

The pan-fried version uses much less oil, is quicker to make, and still gets you that caramelized glaze. The outside is still crunchy at first, but the sugar coating softens a bit as it sits. It’s a little less crisp than the deep-fried method, but just as tasty. This method is popular amongst home cooks in Japan as it doesn’t require deep frying.

Ingredients and Substitutions

Here’s what you’ll need to make daigaku imo:

• Japanese Sweet Potatoes: These have a purple skin and a pale yellow to white interior. They’re naturally sweet and creamy when cooked. You can find them at most Asian supermarkets or even some local grocery stores, sometimes labeled as Murasaki sweet potatoes.
• Granulated White Sugar
• Mirin: Adds depth and a subtle sweetness that enhances flavour.
• Soy Sauce: Used in place of salt to balance the sweetness of the sugar coating.
• Black Sesame Seeds: Sprinkled on top for a nutty aroma and flavor that complements the caramelized sugar coating.
• Rice vinegar (optional): Helps prevent the sugar syrup from crystallizing.
• Oil: For deep frying or pan frying the sweet potatoes. Neutral oils like vegetable, canola, or light olive oil work best.

How to Make Candied Japanese Sweet Potatoes

Here’s a rundown on how to make daigaku imo:

• Prep the sweet potatoes: Cut into wedges using the rangiri technique, then soak in salted water for 5-10 minutes to remove starch. Drain and pat dry.
• Deep-fried version: Start the potatoes in cold oil, bring to temperature, and fry until tender and golden. Finish with a quick high-heat fry for extra crispiness. Make the syrup, then toss the potatoes until coated. Top with black sesame seeds.
• Pan-fried version: Place sweet potatoes in a pan with oil, sugar, soy sauce, and vinegar. Cook covered until tender, then uncover to let the syrup thicken. Add butter (if using) and cook until caramelized. Sprinkle with black sesame seeds.

VIDEO: Watch How to Make It

How to Store and Reheat Leftovers

Daigaku imo is best eaten fresh, but if you have leftovers:

1. Short-term storage: They don’t keep well in the fridge, but if needed, store in an airtight container for up to 2 days. This prevents moisture loss and keeps the glaze from getting too sticky.
2. Freezing: For longer storage, freeze once completely cooled. Place in an airtight container and freeze for 2–3 weeks. Thaw in the fridge before eating. If eaten partially frozen, they have a fun ice-cream-like texture.
   • Tip: Using honey instead of sugar, or adding a small splash of vinegar to the sugar syrup, helps keep the glaze smooth instead of crystallizing after freezing.
   • Note: Deep-fried pieces may dry out a little after thawing, so pan-frying or reheating in a microwave or oven gives better results.

Recipe FAQ

More Japanese Sweet Potato Recipes

• Baked Japanese Sweet Potatoes (Yaki Imo)
• Rice Cooker Japanese Sweet Potatoes
• Japanese Sweet Potato Rice
• Fondant Japanese Sweet Potatoes
• Suito Potato (Japanese Sweet Potato Dessert)
• Imo Kenpi (Sweet Crispy Potato Sticks)
• Sweet Potato Mochi

Enjoy! If you make this Daigaku Imo recipe, I’d love to hear what you think! Leave a comment and rating below, and if you share it on social media, tag me on Instagram @Okonomikitchen. I can’t wait to see your creations!

Daigaku Imo (Japanese Candied Sweet Potatoes)

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5 from 23 reviews

• Author: Lisa Kitahara
• Total Time: 30 minutes
• Yield: 1 serving
• Diet: Vegan

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Description

Daigaku Imo, or Japanese Candied Sweet Potatoes, are crispy on the outside, tender inside, and coated in a glossy caramelized sugar glaze with sesame seeds. This easy Japanese snack is sweet, nutty, and irresistibly crunchy.

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Ingredients

Units USM

Deep Fried

• 1 medium (300 g) Japanese sweet potato
• 1 1/2 – 2 cups neutral oil, for frying
• 3 tbsp (39 g) granulated sugar
• 1 tbsp (15 ml) mirin
• 1/4 tsp rice vinegar (optional, see notes)
• 1 1/2 tbsp (22 ml) water
• 1 tsp Japanese soy sauce
• 1 tsp black sesame seeds, for garnish
• salt, for soaking water

Pan Fried

• 1 medium (300 g) Japanese sweet potato
• 2 tbsp (30 ml) neutral oil
• 3 tbsp (39 g) sugar
• 1/2 tsp Japanese soy sauce
• 1 tbsp salted butter (optional)
• 1/4 tsp rice vinegar (optional, see notes)
• 1 tsp black sesame seeds, for garnish
• salt, for soaking water

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Instructions

Prep (for both methods)

1. Fill a medium bowl with water and add 1% salt (e.g., 10 g salt per 1 L water).
2. Cut sweet potato into 1-inch wedges using the rangiri technique. Hold your knife at an angle, make a diagonal cut, then roll the sweet potato a quarter turn before making the next diagonal cut. Repeat until the whole potato is cut—this creates evenly sized, faceted pieces that cook more quickly and evenly.
3. Soak the pieces in salted water for 10–15 minutes.
4. Drain and pat dry thoroughly with paper towels.

Deep Fried Method

1. Place the sweet potatoes into a wide pot. Add enough neutral oil to cover the potatoes completely.
2. Turn heat to medium and bring oil up to 160–170°C. Fry potatoes for 10–15 minutes, or until a skewer pierces through with little resistance.
3. Increase heat to 190°C and fry for about 1-1.5 more minutes until golden and crisp. Remove and drain on a wire rack or paper towel.
4. In a clean pan, combine sugar, mirin, water and rice vinegar (if using) and stir with a spatula. Place on to burner over medium and heat until large, slow bubbles begin to form. If you have a infrared thermometer or candy thermometer, heat until it reached 300-310 F or until you can draw a line on the pan with the spatula. Drizzle in the soy sauce and then add fried sweet potatoes. Turn off the heat and toss until coated evenly in the syrup. Sprinkle with sesame seeds. 
5. Transfer to parchment-lined tray/plate, separating pieces so they don’t stick. Enjoy!!

Pan Fried Method

1. In a pan, mix oil, sugar, rice vinegar (if using) and soy sauce. Add the sweet potatoes. Cover with a lid thats been wrapped with a towel* and set over medium heat.
2. Once it begins bubbling, swirl the pan, then reduce heat between low to medium-low. Cook undisturbed for 6-8 minutes.
3. Remove the lid (wipe off any excess water from the steam if using a lid without towel wrapped). Flip potatoes and add butter in 3 different spots of the pan Cover again and cook for another 4-5 minutes or until tender. 
4. Remove lid, tilt pan to spread melted butter, and cook uncovered for 2–3 minutes until golden and lightly crisp.
5. Quickly transfer to a parchment-lined tray/plate. Optionally, drizzle with any remaining syrup from the pan. Sprinkle with sesame seeds and enjoy!

Notes

• Rice vinegar: Adding 1/4 tsp vinegar to the syrup helps prevent crystallization, leaving the coating glossy and smooth. If omitted, the sugar syrup will harden into a crisp candy shell (traditional style)
• Towel wrap pan lid: This will prevent the water from the steam from dripping into the pan and ensure a crispy finish. If you don’t have a towel that wraps around your lid, you can wipe the lid every time water forms on the lid. 

• Prep Time: 15 minutes
• Cook Time: 15 minutes
• Category: Dessert
• Method: Frying
• Cuisine: Japanese

Nutrition

• Serving Size: 1 recipe
• Calories: 889
• Sugar: 61 g
• Sodium: 366 mg
• Fat: 39.7 g
• Saturated Fat: 9.2 g
• Unsaturated Fat: 29.7 g
• Trans Fat: 0.8 g
• Carbohydrates: 128 g
• Fiber: 6.6 g
• Protein: 4.9 g
• Cholesterol: 30 mg