Soak the soybeans (overnight): Rinse 1 cup dried soybeans. Cover with plenty of water and soak 8–12 hours. Drain.

Blanch and peel (optional but recommended): Boil the soaked beans for 5 minutes, drain, then rinse with cold water. Gently rub to loosen skins and discard. Peeling yields a smoother, less beany broth.

Cook the soybeans fully: Simmer peeled beans in fresh water until tender, 25–35 minutes. They should mash easily. Drain and cool.

Blend the broth: Add cooked beans to a blender with 1–1.5 cups cold water to start. Blend until silky, 1–2 minutes. Add more cold water until it’s drinkable but creamy, like a light smoothie. Season with 1/2–3/4 teaspoon salt. Chill in the fridge.

Prepare garnishes: Julienne cucumber. Lightly crush or grind toasted sesame seeds. Keep everything cold.

Cook the noodles: Boil somyeon per package (usually 3–4 minutes). Stir to prevent clumping. Drain, then rinse under very cold water until bouncy and cool. Rub gently to remove excess starch. Drain well.

Assemble: Divide noodles into bowls. Pour in chilled soy broth until noodles are just submerged. Add a few ice cubes if it’s a hot day.

Finish and serve: Top with cucumber and sesame seeds. Taste and adjust salt. For a nutty lift, add a few drops of toasted sesame oil. Serve immediately, very cold.

Shortcut method: Blend 2–2.5 cups unsweetened soy milk with 1–2 tablespoons toasted sesame seeds, a small handful of soaked cashews or peanuts (optional), and salt to taste. Chill, then proceed from step 6.