Goguma Mattang

고구마 맛탕, the Korean caramelised sweet potato: cubes of goguma fried until golden and yielding, then tossed in a thick, crackling sugar caramel that sets to a translucent shell and shatters cleanly at the bite, finished with sesame seeds and a whisper of sesame oil

Origin: Joseon Korea — the Korean Peninsula

From the journey of Sweet Potato.

Mattang (맛탕) refers to the Korean technique of coating deep-fried ingredients in a crackling sugar caramel; the word appears in compound with the ingredient name, goguma mattang (sweet potato), yeon-geun mattang (lotus root), and belongs to the broader tradition of Korean banchan (side dishes) and gangsik (snack foods) that are served alongside rice or enjoyed as between-meal snacks. Goguma mattang is among the most popular of the mattang preparations and is widely sold as a street food (pojangmacha) and as a school canteen snack throughout Korea. The goguma (고구마) arrived in Korea in 1763, introduced by the official Cho Eom from Japan following his diplomatic mission to Tsushima and Osaka. It spread rapidly across the Korean Peninsula as a famine-prevention crop, as it had done in Japan before it, and became established as a staple of the Korean diet within a generation. Today Korea maintains a sophisticated goguma culture: roasted goguma (gun-goguma) sold from charcoal-fired drum ovens on winter streets, goguma latte, goguma tteok (rice cakes), and goguma jeon (pancakes) all testify to the tuber's deep integration into Korean food culture. Goguma mattang differs from the Japanese daigaku imo in several respects: it uses a purer, lighter caramel without soy sauce, the caramel is often taken to a slightly lower temperature to produce a chewier rather than harder shell, and sesame oil may be added for fragrance at the very end. The result is sweeter and more straightforwardly confectionery than its Japanese counterpart, though the technique and the pleasure are closely related.

Ingredients

Sweet Potato

  • 600 g sweet potatoes (goguma), peeled and cut into 3–4 cm cubes
  • 4 tbsp cornflour (cornstarch)
  • 1 litre neutral oil, for deep-frying

Caramel

  • 120 g white caster sugar
  • 3 tbsp water
  • 1 tbsp neutral oil
  • 1 tsp sesame oil (added at the end)

To Finish

  • 1 tbsp toasted white sesame seeds

Method

  1. Toss the sweet potato cubes in the cornflour until evenly coated; shake off any excess. Heat the oil in a wok or deep saucepan to 175°C. Deep-fry the sweet potato in two batches for 4–5 minutes each until golden-brown and cooked through. Remove with a slotted spoon and drain on kitchen paper. Keep warm.
  2. In a clean wok or large frying pan over medium heat, combine the sugar, water, and oil. Cook without stirring, swirling the pan occasionally, until the caramel reaches a clear, medium amber colour, slightly paler than the daigaku imo caramel, about 6–7 minutes. The caramel for mattang is taken to a lower temperature than the Chinese or Japanese versions to produce a slightly chewy rather than glass-hard shell.
  3. Remove the caramel from the heat. Add the sesame oil and swirl to incorporate. Immediately add the fried sweet potato cubes and toss to coat completely and evenly.
  4. Spread immediately on a lightly oiled plate or sheet of baking paper. Scatter with sesame seeds while the caramel is still liquid. Allow to cool for 2–3 minutes until the caramel has set to a slightly chewy, translucent shell.
  5. Serve warm as a side dish (banchan), a snack, or a dessert. Goguma mattang is also excellent at room temperature once the caramel has fully set.

Notes

The key distinction between goguma mattang and daigaku imo or bā sī hóng shǔ is the absence of soy sauce from the caramel and the addition of sesame oil at the end: the result is sweeter, lighter in colour, and fragrant with sesame rather than salty-savoury. Some recipes add a tablespoon of rice syrup (mulyeot, 물엿) alongside the sugar for a chewier, more elastic caramel coating; this is a good technique for producing a mattang that stays chewy rather than setting hard, and is particularly useful in cold weather when a hard caramel can become tooth-breaking. Goguma mattang is best eaten within 30 minutes of making.

The Gastrographer

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