Oi Naengguk is a classic Korean cold cucumber soup. The bright, clean flavor of fresh cucumber paired with rehydrated seaweed in a chilled, savory broth makes this an ideal dish for hot summer days.
When the temperature climbs, chilled dishes like Oi Naengguk are lifesavers. This simple soup highlights crunchy cucumbers in a tangy, slightly sweet broth. While you can make it with cucumber alone, adding a little rehydrated seaweed gives it extra texture and umami.
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The tender, slippery texture of rehydrated seaweed contrasts nicely with the crisp cucumber. The broth—lightly seasoned with soy sauce, vinegar, a touch of sugar, garlic, and toasted sesame—strikes a balanced sweet-and-sour note that’s deeply refreshing.
Oi Naengguk is a classic summer banchan (side dish). It’s light, quick to prepare (about 15 minutes), and wonderfully cooling. Serve it icy cold for the best experience.
Key Ingredients
- Cucumber: Korean cucumbers are ideal, but English or Persian cucumbers with thin skins work well too.
- Dried Seaweed (Miyeok): Long, ribbon-like dried seaweed that rehydrates into soft strands; commonly sold in Korean or Asian markets. Wakame can be used as a substitute if needed.
- Dried Sea Kelp (Dashima): A piece of kelp makes a simple, umami-rich stock for the broth.
- Korean Soup Soy Sauce (Gukganjang): A salty, savory soy sauce used to season the soup.
How to make Korean cold cucumber soup
Sea Kelp Soup Base
Soak a piece of dried kelp (dashima) in mineral or filtered water to make a light-stock base. Set it aside while you prepare the other ingredients.
Soak Miyeok Seaweed
Soak the dried miyeok in cold water for 10–15 minutes until it rehydrates and expands. Drain, squeeze out excess water, and cut into bite-sized lengths if the strands are too long.
Rehydrated miyeok will swell to several times its dry size. Trim as needed and discard the soaking water.
Season the Seaweed
In a large bowl, combine the rehydrated seaweed with minced garlic, soup soy sauce (gukganjang), sugar, rice or white vinegar, gochugaru (Korean chili flakes) if using, and toasted sesame seeds. Toss to coat evenly.
Complete the Cucumber Soup
Add thinly sliced cucumber and chopped green onion to the seasoned seaweed. Pour in the kelp stock until you reach your preferred soup consistency, then mix and taste. Adjust salt, vinegar, or sugar to balance the flavors.
Recipe Tips and Advice
- Use filtered or mineral water: A clean-tasting water improves the broth’s clarity and flavor.
- Make ahead: You can prepare the soup a couple of hours in advance and chill it in the refrigerator to deepen the flavors.
- Keep it cold: Add a few ice cubes when serving to keep the soup icy—use sparingly so the broth doesn’t get overly diluted.
What to Pair with Korean cucumber soup
Oi Naengguk is typically served as a side dish and complements many Korean meals. Good pairings include:
- Bibimbap: A warm mixed rice bowl with vegetables and protein; the cold soup balances the heat and richness.
- Grilled meat (Bulgogi or galbi): The refreshing soup cuts through the savoriness and fattiness of grilled meats.
- Steamed rice and banchan: Simple white rice and other small side dishes make a complete, balanced meal.
Korean Cold Cucumber Soup (Oi Naengguk)
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Ingredients
- 1/2 English cucumber , thinly sliced into matchsticks
- 1 roasted seaweed
- 1 dried sea kelp (dashima)
- 3-4 cup mineral water
- 1 tbsp Korean soup soy sauce (gukganjang)
- 2 tbsp sugar
- 3 tbsp rice or white vinegar
- 1 clove garlic , finely minced
- 1 tsp Korean chili flakes (gochugaru)
- 1 tbsp toasted sesame seeds
- 1 green onion , finely chopped
- salt to taste
Instructions
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Soak the sea kelp in mineral water and set aside.
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Soak the dried seaweed cuts in cold water for 10–15 minutes. Drain and squeeze out excess water. Cut to a smaller size if needed.
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Place the seaweed in a large bowl and add the soup soy sauce, sugar, vinegar, garlic, chili flakes, and sesame seeds; mix well.
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Add the cucumber and green onion to the seasoned seaweed. Pour in the kelp stock, mix, and taste. Adjust seasoning as desired.
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Note: You can make this a couple of hours ahead and chill it in the fridge. Add a few ice cubes when serving to keep it extra cold. Enjoy!