Cool, crisp, and refreshing, oi-naengguk (오이냉국) is one of Korea’s most beloved summer soups. Made with chilled cucumber slices in a tangy, savory-sweet broth, it’s the perfect antidote to sweltering heat. Traditionally enjoyed as a light side dish, oi-naengguk balances bright vinegar notes with the natural sweetness of cucumber, creating a flavor that’s both invigorating and comforting.
In our restaurant, we often served it as a little “bonus dish” on hot days—a gesture of hospitality that delighted guests and reminded them of the simple joy of Korean home cooking. Whether paired with rice, barbecue, or enjoyed on its own, oi-naengguk embodies the essence of summer in Korea: cool relief, shared generosity, and a harmony of flavors in every sip

Ingredients
1 medium Cucumber (about 1 1/2 cups - 7 ounces)
3 cloves garlic
1 medium green onion
1 green chili pepper
1 red hot chili pepper
6 ice cubes

Broth:
1 1/2 tablespoon vinegar
1 teaspoon salt
1 teaspoon fish sauce
1 teaspoon sugar
1 1/2 cup cold water

Directions:

Preparation:
Wash cucumber in cold water.
Slice the cucumber in half crosswise, then thin slice (about 1/8" thick) each half lengthwise.
Cut slices lengthwise into "noodles" about 1/8" thick. (Julienne)
Place cucumber strips into a medium mixing bowl.

Mince, fine chop, or thin slice the garlic cloves and add to the bowl.
Cut the green chile pepper into thin slivers and add to the bowl.
Cut the green onion into roughly 1/4 inch segments and add to the bowl.
Gently toss the contents of the bowl until well mixed.

Mix Broth
In a separate bowl, mix all broth ingredients until sugar and salt are dissolved.

Final:
Separate the cucumber mix into two equal portions and place into serving bowls.
Fine chop the red chili pepper.
Pour one half of the broth over each serving.
Sprinkle red pepper into each bowl, add ice cubes, and serve.

Variation:
Mix the broth before prepping the vegetables. Pour broth into an ice tray and freeze.
Add one additional cucumber, then slice both in half lengthwise. Remove the pulpy seed area and reserve it, then julienne as above.
Prep vegetables as above and divide into serving bowls.
Place the frozen broth cubes into a strong blender, add one or two tablespoons water, and blend into slush.
Mix the cucumber pulp into the slush.
Spoon the slush equally into the serving bowls, sprinkle with chopped red pepper, and serve.

Tips

Substitutions/Additions:
Substitute Japanese eggplant or fresh zucchini for the cucumber.
Add Kombu to cucumber.