Blanch the green beans in boiling water until they brighten and taste tender, about 5 minutes. Transfer to an ice bath to stop the cooking. Drain and pat dry, store in refrigerator until ready to use. Toast the sesame seeds and set aside.
Combine all the dressing ingredients. When ready to serve, toss the green beans with the dressing and sprinkle sesame seeds on top.
This would be a great dish for parties or when you want do all the prep work earlier in the day, then just toss together prior to serving.