The rather cryptically named daigaku imo, or university potatoes, have been a staple snack food across the university towns of Japan since the 1920s. Deep fried sweet potatoes, tossed in caramel flavoured with soy sauce which quickly becomes brittle in the air; what’s not to love about them? The soy caramel coating brings to mind the salted caramel chocolates which have become popular in the UK over the last decade, and the glazed potatoes make me think of American Thanksgiving style candied yams. Traditionally these are made with the red-pink skinned, white fleshed sweet potatoes most common in Japan, but we ate some made with the gloriously bright purple murasaki imo in Kamakura and couldn’t resist recreating those in part here. Murasaki imo have an almost winey, lychee flavour to them which works wonderfully with the salty soy sauce.
- 800g sweet potatoes (don’t use the orange fleshed ones as their moisture content is just too high)
- 4 tablespoons sugar
- 2 tablespoons rice syrup (golden syrup or corn syrup will work fine too)
- 1 teaspoon soy sauce
- 1 tablespoon gomashio (sesame seeds and coarse sea salt)
- vegetable oil for deep frying
- Wash the sweet potatoes well, remove any unsightly bits or roots but leave the peel on. Chop them into irregular angular pieces slightly larger than bite sized, then soak in a bowl of cold water for around 5 minutes to remove excess starch.
- Pour around an inch of oil into a pan suitable for deep frying and place over a medium heat to get hot. While the oil is heating up, drain the potato pieces and dry them well with kitchen roll. Fry the sweet potatoes gently, adjusting the temperature as you go if they’re browning too fast; you want to cook them for around 7-8 minutes and end up with lightly golden, slightly crispy pieces.
- While the potato is cooking, mix the sugar, syrup and soy sauce in a large pan and place on a medium heat. Bring the syrup mixture to the boil and allow to bubble and thicken until the potatoes are cooked.
- Using a mesh, remove the potatoes from the oil, then quickly pat them dry with kitchen roll before adding them to the caramel and stirring to coat fully. Sprinkle them liberally with the gomashio before the caramel sets and serve immediately.
If left to go cold, these daigaku imo become more saucy and sticky as they absorb moisture from the air, making a great addition to a bento.
Serves 4-6 people as a snack or side dish.