1 pound soybean sprouts
2 tablespoons soy sauce
1/4 cup sesame oil
2 tablespoons Korean chile powder
1 1/2 teaspoons garlic, minced
2 teaspoons sesame seeds
1/4 cup chopped green onion
2 teaspoons rice wine vinegar, or to taste
Bring a large pot of lightly salted water to a boil. Add the bean sprouts, and cook uncovered until tender yet still crisp, about 15 seconds. Drain in a colander, then immediately immerse in ice water for several minutes until cold to stop the cooking process. Once the bean sprouts are cold, drain well, and set aside.
Whisk soy sauce, sesame oil, chile powder, garlic, and sesame seeds together in a large bowl. Stir in bean sprouts and toss until well coated with the sauce. Sprinkle with green onions and season with rice wine vinegar. Refrigerate before serving.