Steam the green beans covered in a half-inch of boiling water for 2 minutes. Transfer the beans to a colander and run under cold water. Drain well.
Heat a wok-shaped skillet or large nonstick frying pan over high heat. Add the oil, one turn of the pan in a slow stream, then add several drops of the sesame oil and the crushed pepper flakes. The pan will smoke. Add the beans and stir fry for 2 minutes. Add the sesame seeds and coarse salt and toss to evenly coat the beans.