Introduction

Goguma mattang (고구마 맛탕) is a much-loved Korean snack of fried sweet potato chunks coated in a shiny, crackly sugar glaze and sprinkled with black sesame seeds. The magic is in the mattang syrup – a quick caramel of sugar, oil and often Korean rice or starch syrup that sets into a thin candy shell. It is a classic after-school treat, street snack and home dessert in autumn and winter, when Korean sweet potatoes are at their best. Here is what the glaze is made of and how to get it right.

Mattang Syrup at a Glance

What it is

• A Korean caramel-style glaze for candied fried sweet potatoes

Main ingredients

• Sugar, cooking oil, rice syrup or mulyeot, a pinch of salt, black sesame seeds

Taste

• Sweet, lightly caramelized and crunchy when set

Main uses

• Goguma mattang, candied potatoes, glazed nuts, glazed fried rice cakes

What is Mattang Syrup Made Of?

The simplest mattang syrup is just sugar melted in a little oil until it turns into a light caramel. Many home cooks add a spoonful of Korean jocheong (rice syrup) or mulyeot (starch syrup), which keeps the glaze glossy and less likely to crystallize. Common styles:

• Crunchy shell style: sugar and oil only, cooked to light amber, sets hard like candy.
• Glossy sticky style: sugar plus rice syrup, softer and chewier.
• Honey style: a little honey added at the end for aroma.

What Does Mattang Syrup Taste Like?

It tastes like a delicate, buttery-free caramel. Wrapped around a hot, fluffy sweet potato it forms a thin glass-like shell that cracks when you bite in, followed by the soft, chestnut-like flesh of the potato. Black sesame seeds add a toasty crunch, and a pinch of salt keeps the sweetness from feeling flat.

Popular Korean Dishes That Use Mattang Syrup

Goguma Mattang

Fried sweet potato chunks in candy glaze – the signature dish.

Gamja Mattang

The same idea made with regular potatoes.

Glazed Fried Tteok

Pan-fried rice cakes tossed in a quick sugar glaze, a cousin of tteok-kkochi.

Candied Nuts

Walnuts or peanuts coated in the same syrup for a crunchy banchan or snack.

Easy Goguma Mattang Recipe (Serves 3–4)

Ingredients

• 2 medium Korean or Japanese sweet potatoes (about 1.3 lb / 600 g)
• Neutral oil for frying (about 2 inches / 5 cm deep in a heavy pot)

Mattang Syrup

• 4 Tbsp sugar
• 2 Tbsp rice syrup or mulyeot
• 1 Tbsp neutral oil
• Pinch of salt
• 1 tsp black sesame seeds

Instructions

1. Scrub the sweet potatoes (peeling is optional) and cut into 1-inch (2.5 cm) chunks. Soak in cold water for 15 minutes to remove surface starch, then dry very well – water makes hot oil spatter.
2. Heat the oil in a heavy, deep pot to about 340°F (170°C). Never fill the pot more than halfway, keep a lid nearby, and never leave hot oil unattended.
3. Fry the sweet potatoes in batches for 6–8 minutes, until golden and a chopstick slides in easily. Lift out with a slotted spoon onto a rack. For extra crunch, fry again for 1–2 minutes.
4. In a clean, wide pan, add the sugar, syrup, 1 Tbsp oil and salt. Cook over medium-low heat without stirring too much until the sugar melts and bubbles to a light amber color, 2–4 minutes.
5. Turn off the heat, add the hot sweet potatoes and toss quickly to coat. Sprinkle with black sesame seeds.
6. Spread on parchment paper, separating the pieces so they do not stick together. Let cool 5 minutes so the glaze sets. Hot sugar can cause burns, so do not touch it until it has cooled.

Tip: For a lighter version, air-fry the oiled sweet potato chunks at 380°F (190°C) for 15–18 minutes, shaking once, then toss in the syrup.

Where to Buy Mattang Syrup Ingredients

United States

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Amazon
Search Korean rice syrup on Amazon
Search black sesame seeds on Amazon

H-Mart
Search Korean sweet potatoes on H-Mart

Canada

Search Korean rice syrup on Amazon.ca

Europe

Search Korean rice syrup on Amazon.co.uk

How to Store Mattang

Mattang syrup is best made fresh, right before tossing. Goguma mattang tastes best the day it is made; leftovers can be kept in an airtight container at cool room temperature for a day or in the fridge for 2–3 days, though the shell softens. Re-crisp in an air fryer or oven at 350°F (175°C) for a few minutes. Cool used frying oil completely before straining and storing or disposing of it.

Mattang Syrup FAQ

Why did my mattang syrup crystallize?

Stirring too much or cooking sugar without any syrup can cause grainy crystals. Adding rice syrup and swirling the pan instead of stirring helps.

What is the difference between goguma mattang and Japanese daigaku imo?

They are very similar candied sweet potato dishes. Daigaku imo often uses a soy-sweetened syrup, while Korean mattang is usually a plain sugar caramel with black sesame.

Can I use honey instead of sugar?

Honey burns easily and stays sticky, so it is better as a small addition than a full replacement.

Which sweet potato is best for mattang?

Korean or Japanese sweet potatoes with purple skin and pale yellow flesh, which are drier and fluffier than orange yams.

Conclusion

With just sugar, a little syrup and oil, mattang syrup turns plain sweet potatoes into a crunchy, glossy Korean treat. Try it this autumn, and if you love fried Korean snacks, see our twigim garu guide with goguma twigim.