In a large kettle simmer potatoes in salted water to cover until tender when pierced with a fork, about 10 minutes, and drain in a large colander.
In a large saucepan cook beans in 3 inches salted boiling water over high heat until crisp-tender, about 3 to 5 minutes. With tongs or a slotted spoon transfer beans to colander with potatoes and drain well.
In a large bowl toss together warm potatoes, beans, herbs, dressing and salt and pepper to taste. Salad may be made 1 day ahead and chilled, covered.
Serve salad warm or at room temperature.
In a bowl whisk together all the ingredients except the oil. Slowly add the oil in a stream.
recipe courtesy of Gourmet Magazine