Make Oi Naengguk, a refreshing 5-minute Korean cucumber soup using simple UK supermarket ingredients—perfect after a warm summer run.
Key Takeaways
- Quick Korean summer soup: Oi naengguk combines crisp cucumber with a chilled sweet-and-sour broth and takes about five minutes to prepare.
- Easy UK supermarket ingredients: English cucumber, rice vinegar and light soy sauce create a refreshing bowl without specialist shopping.
- Flexible serving option: Enjoy it as a cooling side dish or pair it with rice and a protein source for a more satisfying meal.
A Refreshing Korean Soup for Hot Days
Oi naengguk (오이냉국) literally means “cold cucumber soup” in Korean: oi means cucumber, while naengguk refers to a chilled soup. It is a refreshing Korean dish commonly enjoyed during warm summer weather. Thinly sliced cucumber is combined with cold water, vinegar, soy sauce and a little sweetness to create a clean, refreshing broth. Toasted sesame seeds add a nutty finish, while ice keeps every spoonful cool
Unlike soups that require a long simmer, oi naengguk involves no cooking and can be ready in about five minutes. It works particularly well when a hot meal feels too heavy, whether you serve it with lunch, alongside a Korean barbecue meal or after a summer walk or run.
The recipe is also easy to make in the UK. A standard English cucumber has a slightly different shape and texture from Korean cucumber, but it remains crisp and readily absorbs the seasoning.
What Does Oi Naengguk Taste Like?
The appeal of oi naengguk comes from the balance of four simple flavours:
- Vinegar provides a bright, refreshing acidity.
- Soy sauce and salt create savoury depth.
- A small amount of sugar or honey rounds out the sharpness.
- Cucumber and cold water keep the soup clean and light.
Rice vinegar produces a mild, smooth flavour. Apple cider vinegar also works, but it is fruitier and often tastes stronger, so start with a smaller amount. The final broth should be pleasantly tangy rather than sharply acidic or noticeably sweet.
Why Cucumber Works So Well in a Summer Soup
Cucumber has a high water content and a crisp texture, making it especially enjoyable in chilled dishes. It also contributes small amounts of nutrients including vitamin K and potassium. Most of the fluid in this recipe comes from the cold broth, while the cucumber adds freshness and volume.
The soup is light enough to accompany richer foods such as grilled tofu, fish or chicken. It can also add contrast to a rice-based meal without requiring an additional cooked vegetable dish.
For another Korean summer recipe, try Healthy Subak Hwachae, a lower-sugar Korean watermelon punch.
UK Shopping Guide
You can find the main ingredients at Tesco, Sainsbury’s, Waitrose, M&S and most other UK supermarkets.
| Ingredient | Easy UK option | What to look for |
| Korean cucumber | English cucumber or baby cucumber | Choose a firm cucumber with smooth, fresh-looking skin. |
| Rice vinegar | Rice vinegar from the world-food aisle | Use unseasoned rice vinegar when possible so you can control the sweetness. |
| Soup soy sauce | Light soy sauce | Start with a small amount and add salt only after tasting. |
| Toasted sesame seeds | Plain sesame seeds | Toast them briefly in a dry pan if they are sold untoasted. |
Rice Vinegar vs Apple Cider Vinegar
Rice vinegar has a softer, cleaner acidity that suits the traditional flavour of oi naengguk. Apple cider vinegar has a fruitier aroma and a more pronounced tang. Both can be used, but they are not identical in flavour.
If using apple cider vinegar, begin with one tablespoon, taste the broth and add more gradually. There is no need to choose raw or unpasteurised apple cider vinegar for this recipe.
Easy 5-Minute Oi Naengguk Recipe
Serves: 2
Preparation time: 5 minutes
Dietary notes: Vegan; use certified gluten-free tamari if required
Ingredients
- 1 large English cucumber, thinly sliced or cut into fine matchsticks
- 480ml cold water
- 2 tablespoons rice vinegar, or 1–2 tablespoons apple cider vinegar
- 1 tablespoon light soy sauce
- 1–2 teaspoons sugar or honey, to taste
- Up to ¼ teaspoon fine sea salt, added after tasting
- 1 small garlic clove, finely minced (optional)
- 1 spring onion, thinly sliced (optional)
- 1 mild green chilli, thinly sliced (optional)
- 1 tablespoon toasted sesame seeds
- 4–6 ice cubes
Method
1. Prepare the Cucumber
Wash the cucumber and leave the skin on for colour and texture. Cut it into thin rounds or fine matchsticks. If the centre is particularly soft and watery, remove some of the seeds with a teaspoon before slicing.
2. Make the Seasoning
Add the cucumber, vinegar, soy sauce, sugar or honey and garlic (optional) to a large bowl. Mix gently until the sweetener has dissolved.
3. Add the Cold Water
Pour in the cold water and stir well. Taste before adding any salt, as the soy sauce already provides seasoning. Add a small pinch at a time until the broth tastes balanced.
4. Finish and Serve
Add the ice immediately before serving. Sprinkle over the sesame seeds and finish with spring onion (optional) or green chilli (optional). Divide between two bowls and serve straight away.
K-Well’s Flavour Tip: Vinegar brands vary in strength. Adjust the vinegar, sweetness and salt gradually until the broth tastes lightly sour, savoury and refreshing. Chilling the water in advance helps preserve the flavour because you will need less ice.
How to Serve Oi Naengguk
Oi naengguk is traditionally served as a light side dish rather than a complete meal. Its crisp, acidic flavour works particularly well with warm rice and savoury main dishes.
Try serving it with:
- steamed rice or Korean multigrain rice (japgokbap)
- grilled tofu, chicken or fish
- a vegetable bibimbap bowl
- gimbap or simple rice balls
- Korean barbecue dishes
For a lighter lunch, pair the soup with tofu and a small bowl of rice. The combination adds protein and carbohydrates while keeping the meal fresh and simple.
Enjoying Oi Naengguk After Exercise
Cold cucumber soup can be appealing after a warm-weather walk, yoga session or run because it contributes fluid and is easy to eat when your appetite is still returning. Soy sauce and salt also contribute some sodium.
For a more complete post-exercise meal, serve it with a source of protein such as eggs, tofu, edamame, fish or chicken. Add rice, sweet potato or another carbohydrate source according to the length and intensity of your activity and your appetite.
After a short, gentle session, the soup can simply accompany your next regular meal. After longer exercise or heavy sweating, additional fluid and a well-balanced meal may be useful. For an everyday caffeine-free drink, see Bori-cha: Korean Roasted Barley Tea.
Storage and Make-Ahead Tips
Oi naengguk tastes best freshly assembled, while the cucumber is still crisp and the broth is cold but not diluted.
To prepare it ahead, slice the cucumber and mix the vinegar, soy sauce and sweetener in a separate covered container. Refrigerate both and combine them with cold water just before serving. Add the sesame seeds, garnishes and ice at the end.
For the best texture, use the sliced cucumber within one day. If storing leftover assembled soup, keep it covered in the refrigerator and enjoy it the same day.
K-Well’s Final Thoughts
Oi naengguk shows how a few everyday ingredients can create a distinctive Korean summer dish. Crisp cucumber, a gently sweet-and-sour broth and toasted sesame seeds come together in minutes, with no hob or specialist equipment required.
Keep the base recipe simple, then adjust the vinegar and seasoning to suit your taste. Served with rice and protein or alongside a larger Korean meal, it is an easy way to bring a cool, refreshing contrast to the table.
FAQ
Q1. Can I Make Oi Naengguk Without Sugar?
Yes. You can omit the sugar, although the broth will taste sharper. Another option is to begin with ½ teaspoon and add more only if needed. A small amount of sweetness is used to balance the vinegar rather than make the soup taste sugary.
Q2. Can I Use Apple Cider Vinegar Instead of Rice Vinegar?
Yes. Apple cider vinegar has a stronger, fruitier flavour, so start with one tablespoon and adjust after tasting. Rice vinegar gives the broth a milder flavour that is closer to the usual Korean style.
Q3. Do I Need to Peel the Cucumber?
No. Leaving the skin on adds colour and helps the slices retain a pleasant bite. If the skin is particularly thick or waxed, peel it completely or remove it in alternating strips.
Q4. Can I Leave Out the Raw Garlic?
Yes. You can omit the garlic for a cleaner, milder broth. Spring onion or a few finely chopped chives can add gentle savoury flavour instead.
Read Next
- Healthy Subak Hwachae: Low-Sugar Korean Watermelon Punch
- Bori-cha: Why Koreans Drink Roasted Barley Tea
- Korean Multigrain Rice (Japgokbap)
References
- Burdon, C. A., O’Connor, H. T., Gifford, J. A., & Shirreffs, S. M. (2010). Influence of beverage temperature on exercise performance in the heat: A systematic review. International Journal of Sport Nutrition and Exercise Metabolism, 20(2), 166–174. https://doi.org/10.1123/ijsnem.20.2.166
- National Health Service. Dehydration. https://www.nhs.uk/conditions/dehydration/
- U.S. Department of Agriculture, Agricultural Research Service. FoodData Central. https://fdc.nal.usda.gov/
Health & Safety Disclaimer: The content provided on KWellnessKitchen is for informational and educational purposes only and does not constitute medical advice, diagnosis or treatment. Individual hydration and recovery needs vary. Consult a qualified healthcare professional or registered dietitian regarding medical conditions or specific dietary requirements.