Oi-naengguk (Cold Cucumber Soup)

Ingredients

Equipment Needed

• •Sharp knife or mandoline with hand guard
• •Medium mixing bowl
• •Chilled serving bowl or individual soup bowls

Instructions

1. 1

   Chill the bowl

   Put the water and serving bowl in the refrigerator for at least 30 minutes, or start with water that is already ice-cold. Cold is not decoration here. It is the seasoning. A warm naengguk tastes flat no matter how good your vinegar is.

2. 2

   Cut the cucumber

   Wash the cucumber and trim the ends. Taste a thin slice from the stem end; if it is bitter, trim a little more. Cut the cucumber into 2 inch lengths, then into narrow matchsticks about 2 to 3 mm thick. Do not grate it. Thick pieces slip off the spoon, and grated cucumber turns the broth cloudy.

3. 3

   Season the cucumber

   Put the cucumber in a bowl with 1/4 teaspoon of the salt, the garlic, scallion, sesame seeds, and gochugaru if using. Toss with your hand and let it sit 5 minutes. This is not to wilt the cucumber into sadness. It wakes the cucumber juice and lets the garlic and scallion cling. Stir in the sesame oil after the rest, only 1/2 teaspoon, because too much oil floats across a cold soup and covers the clean taste.

   Crush the sesame seeds lightly between your fingers or in a mortar. Whole sesame looks pretty, but crushed sesame gives the broth its nutty finish.
4. 4

   Mix the broth

   In a cold bowl, whisk together the ice-cold water, rice vinegar, guk-ganjang, sugar, and the remaining 1/4 teaspoon salt until the sugar dissolves. Taste it before the ice goes in. It should be sharper and a little saltier than you want to drink straight, because the cucumber and ice will soften it.

5. 5

   Combine and rest

   Pour the broth over the seasoned cucumber and stir. If you have 10 minutes, return the bowl to the refrigerator so the cucumber seasons the broth. If dinner is already on the table, serve it now; this is one safe corner to cut. The unsafe corner is serving it lukewarm.

6. 6

   Serve icy

   Add the ice cubes just before carrying the bowl to the table. Taste once after the ice has begun to chill the soup. If it tastes dull, add exactly 1 teaspoon more rice vinegar or 1/8 teaspoon salt, not both at once. Serve with rice and a few banchan. The broth should be cold enough to wake you up.

Chef Tips

• •Buy cucumbers in the month they taste like cucumbers. Korean oi is best here, with thin skin and a clean snap. Persian cucumbers are the closest easy substitute. A waxed slicing cucumber with large seeds will work only if you peel it and scrape out the watery center.
• •If your vinegar is labeled 2x strength, use 1 tablespoon plus 1 teaspoon instead of the full 2 tablespoons. Korean kitchens often keep strong vinegar, and one careless pour can make the broth harsh.
• •Guk-ganjang seasons the broth without turning it too dark. If you only have regular soy sauce, use 2 teaspoons, then let the remaining salt do the work.
• •The safe shortcut is cold water and ice. The corner you should not cut is the knife work. Cucumber that is too thick makes the soup clumsy; cucumber cut fine but not limp makes the bowl clean.

Advance Preparation

• •The broth can be mixed up to 2 days ahead and kept covered in the refrigerator. Do not add the cucumber or ice until serving day.
• •The cucumber can be cut and salted up to 30 minutes ahead, then kept cold. Longer than that and it loses its crispness.
• •Leftovers will keep 1 day in the refrigerator, but the cucumber softens. Refresh with a few new cucumber matchsticks and 1 teaspoon vinegar before serving.

Frequently Asked Questions

Nutrition Information

1 serving (about 470g)