Bring a pot of water to a boil. Add the bean sprouts and blanch for 2-3 minutes until tender but still crisp. Drain and rinse under cold water to stop the cooking process.
In a large mixing bowl, combine the sesame oil, soy sauce, rice vinegar, sugar, minced garlic, and a pinch of salt. Whisk until the sugar dissolves.
Add the blanched bean sprouts to the bowl and toss gently to coat them in the dressing.
Sprinkle the sesame seeds and chopped green onion over the top and toss again to combine.
Let the salad sit for at least 10 minutes to allow the flavors to meld before serving.