A recipe for Oi Naengguk (Korean Chilled Cucumber Soup)! This refreshing soup pairs a cold and tangy broth with sliced cucumbers and other vegetables.
This Oi Naengguk (오이냉국, Korean Chilled Cucumber Soup) is a fantastic use of summer produce while also cooling off on especially warm days. There is no cooking involved and the overall preparation is roughly around 10 minutes.
Start by forming the soup base. In a large bowl, stir together cold water, garlic, vinegar, soy sauce, plum syrup, sugar, and salt. Adjust the seasonings to taste and refrigerate the bowl while you prepare the remaining ingredients to keep everything cold.
Rehydrate the dried seaweed in a small bowl of water, the add to the soup along with the cucumber, green onion, and pepper.
Serve the Oi Naengguk immediately with ice cubes to keep it extra cold and garnish with a sprinkling of sesame seeds. I also like to add a few cherry tomato halves if I have them on hand.
Notable Ingredients
If possible, try to use Korean cucumbers (Oi, 오이) for the Oi Naengguk. These long, slender cucumbers have a thin, bumpy, light green skin with small, cream colored seeds.
If unavailable, swap for Persian cucumbers. Since Persian cucumbers are smaller, you may want to use one or two extra to get closer to around 10 ounces (283 grams). If those are unavailable, use an English cucumber. The skin is a little thicker, so you may want to peel it first, then slice in half lengthwise and scoop out the seeds before thinly slicing.
Miyeok (미역, Wakame) is an edible seaweed with a slightly sweet and salty flavor. If unavailable, simply omit. I used a pre-cut seaweed so no additional prep was needed other than soaking in water to rehydrate.
Green Plum Syrup/Extract (매실청, Maesil Cheong) is a thick, fragrant syrup with a sweet and tangy flavor. If not available, omit and add a little more sugar and vinegar to taste. Kimchimari also has a recipe for Homemade Maesil Cheong.
Guk-Ganjang (Joseon-Ganjang/국간장) is a Korean soup soy sauce generally made as a byproduct of doenjang (fermented soybean paste). It is made from soybeans, water, and salt. This sauce has more salt and the light color won’t change the color of the broth.
Maangchi also features a way to make your own Guk-Ganjang. If unavailable, swap for regular soy sauce. The color of the broth will be a little darker and you may need to add a pinch or two more salt.
For those in Northern Virginia, I have been able to find all of these ingredients at Lotte and H Mart in Centreville.
I added a thinly sliced green onion, but have also seen the soup with thin slices of 1/4-1/2 of a white onion.
A Few Korean Chilled Cucumber Soup Tips
If the cucumbers are extra bumpy or to remove any remaining residue on the skin, you can rub them with salt and rinse before slicing. Discard the ends, as they may be more bitter.
I cut the cucumbers into thin matchsticks about 2 inches (5 centimeters) long by hand. You can also use a mandoline slicer to quickly get more uniform pieces.
Adjust the heat as desired to personal taste. I added thin slices of a red chili pepper with the seeds included. For less heat, discard the seeds or use a less hot variety of pepper. For a little more spice, you can use a green and a red pepper, increase the amount, or add a pinch or two of red chili flakes (gochugaru).
The broth can be assembled up to a day or two in advance and refrigerated in an airtight container until needed.
Don’t add the ice cubes until immediately before serving. They will start to melt and dilute the flavors in the broth.
The cherry tomatoes are optional, but I like to add them whenever I have extras from the garden. I have also seen this Korean Chilled Cucumber Soup occasionally with a handful of matchstick-sized or grated carrots.
Looking for more cucumber recipes?
Try my:
- Agurkai su Medumi (Lithuanian Cucumbers with Honey)
- Sunomono (Japanese Cucumber Salad)
- Mast-o-Khiar (Persian Yogurt and Cucumber Dip)
This recipe was originally posted in September 2015 and updated in August 2025.
Oi Naengguk (Korean Chilled Cucumber Soup) Recipe
Adapted from Maangchi
Oi Naengguk (Korean Chilled Cucumber Soup)
Ingredients
- 3 cups (710 milliliters) cold water
- 1 clove garlic peeled and grated
- 3 tablespoons (44 milliliters) rice vinegar or apple cider vinegar
- 2 tablespoons (30 milliliters) soup soy sauce
- 1 1/2 tablespoons (22 milliliters) green plum syrup/extract Maesil Cheong
- 1 tablespoon (12 grams) granulated sugar
- 1-1 1/2 teaspoons sea salt add salt to taste, more may be needed if using regular soy sauce
- 5 grams (0.17 ounce) dried seaweed miyeok, wakame
- 1 Korean cucumber about 10 ounces (283 grams), ends discarded and cut into 2 inch (5 centimeter) long matchsticks
- 1 green onion thinly sliced
- 1 Korean red chili pepper thinly sliced
- ice for serving
- roasted sesame seeds for serving
- cherry tomatoes optional, halved
Instructions
- Place the 3 cups (710 milliliters) water in a large bowl.
- Add the garlic, vinegar, soup soy sauce, green plum syrup, granulated sugar, and salt to the water.
- Stir well until the sugar and salt have dissolved. Adjust seasonings to taste, adding a little more salt and/or vinegar if needed. Keep in mind the flavors will slowly dilute as the ice melts.
- Place the bowl in the refrigerator while you prepare remaining ingredients.
- Place the seaweed in a small bowl and cover with water. Set aside for 5-10 minutes, or until rehydrated and tender. Drain and squeeze out any excess water. Cut into bite-size pieces if not already pre-cut.
- Gently stir the cucumber, rehydrated seaweed, green onion, and red pepper into the cold broth.
- Divide the mixture among small serving bowls, add ice cubes, and sprinkle with roasted sesame seeds. If desired, add a few cherry tomato halves.
- Serve immediately after adding the ice.
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