Goguma Mattang (Korean Candied Sweet Potatoes)
Korean candied sweet potatoes with a thin, hard, shatter-crisp sugar shell. Fried twice, tossed in melted sugar, and cooled apart so every piece cracks.
Servings 4 servings
Ingredients
For the Sweet Potatoes
- 1 ½ pounds Korean sweet potatoes (goguma) peeled and roll-cut into 1-inch pieces
- 4 cups neutral oil for frying
For the Sugar Shell
- ⅓ cup granulated sugar
- 1 tablespoon neutral oil
- 1 tablespoon Korean starch syrup (mulyeot) optional, or light corn syrup
- 1 tablespoon toasted sesame seeds white or black
- 1 pinch flaky sea salt optional
Instructions
Fry the Sweet Potatoes
- Peel the sweet potatoes and roll-cut them into 1-inch pieces: cut at a 45 degree angle, roll a quarter turn, and cut again.
- Rinse the pieces in cold water, drain, and dry them thoroughly on a towel. Surface water keeps the candy from setting hard.
- Heat the frying oil to 300F in a deep pot, filling it no more than a third full. Fry the pieces in two batches for 6 to 8 minutes each, until a fork slides in easily.
- Drain on a rack for 5 minutes. Raise the oil to 375F and fry again for 1 to 2 minutes, until the edges are golden and the surface looks dry.
Candy and Cool
- Wipe out a wide skillet. Add the tablespoon of oil, the sugar, and the starch syrup if using, and set it over medium heat.
- Swirl the pan, do not stir, until the sugar melts into a clear pale amber liquid with no grains left.
- Add all the fried sweet potato at once and toss for about 30 seconds until every surface is coated. Shower the sesame seeds over while tossing.
- Turn the pieces out onto a lightly oiled tray or parchment and push them apart so none are touching. Let them set uncovered for 10 minutes, then finish with flaky salt if you like.
- For a glass-hard shell, dip the coated pieces in ice water for 2 seconds before setting them on a rack.
Notes
- Do not stir the sugar: swirl the pan instead. Stirring makes the sugar crystallize back into grains and the shell will never set.
- Cool them separated: any two pieces touching as they cool will fuse into a lump and stay soft where they meet.
- Not daigaku imo: the Japanese version uses soy sauce and mirin for a soft, sticky glaze. Mattang uses plain sugar for a hard shell that cracks.
- Substitute: regular orange sweet potatoes work but hold more water, so they fry softer and the shell is less crisp.
- Never refrigerate: cold pulls moisture into the candy and turns the shell to syrup overnight. Eat the same day.