Cook noodles in a large pot of boiling salted water until just tender, then drain in a colander. Rinse with cold water until cool. Toss in a large bowl with sesame oil. In a small bowl, stir together soy sauce, chile oil, bean sauce, ginger, garlic, and sugar. Pour over noodles, add green onions, and toss well.
If taking on a picnic, transfer noodles to a container for transport. To assemble, put noodles in serving bowls and offer with desired toppings and chopsticks.