Prepare a large bowl of ice water. Bring a large pot of salted water to a boil, and then add the bean sprouts and cook until al dente, about 1 minute. Remove with a slotted spoon and immediately add to the ice water. Drain in a strainer and pat dry.
Add the bean sprouts to a medium bowl, toss with the sesame oil, fish sauce, gochugaru, mirin, garlic and scallions and sprinkle with sesame seeds.