Fill a medium bowl with ice water. Fill a large skillet with 1/4 inch of salted water and bring to a boil. Add the green beans, cover and steam until crisp tender, about 4 minutes. Drain and transfer to the ice water until chilled, about 3 minutes. Drain and pat the green beans dry.
When ready to serve, dry out the skillet and heat the peanut oil until shimmering. Add the green beans and cook over moderate heat, tossing occasionally until heated through, about 3 minutes. Add the sesame seeds, sesame oil and season with salt and pepper. Transfer to plates and serve.