Prep the sprouts: Rinse the soybean sprouts under cold water. Remove any wilted or brown sprouts. Drain well.

Build a light broth: In a medium pot, add water and the kombu (or anchovies). Bring to a gentle simmer over medium heat. Let it infuse for 5–7 minutes, then remove the kombu or anchovies so the broth stays clean and not bitter.

Add aromatics: Stir in the garlic and the white parts of the scallions. Simmer for 1 minute to soften the edges.

Cook the sprouts: Add the soybean sprouts. Bring back to a simmer and cook for 4–6 minutes, until the sprouts are just tender but still crisp. Do not overcook.

Season: Add salt and, if using, soy sauce. Taste and adjust—this soup should be light but well seasoned.

Finish: Stir in gochugaru and chili if you want gentle heat. Sprinkle in the green parts of the scallions. Turn off the heat and add a few drops of sesame oil if you like.

Serve hot: Ladle into bowls and enjoy as is or with a bowl of steamed rice on the side.