Cook pasta as directed on package, adding green beans during last 5 to 7 minutes of cooking time. Cook until pasta and green beans are tender. Drain; rinse with cold water to cool. Drain well.
In large bowl, mix cooked orzo and green beans and all remaining salad ingredients except feta cheese; stir gently. Cover; refrigerate at least 1 hour or until chilled.
Meanwhile, in small jar with tight-fitting lid, shake all dressing ingredients until well mixed. Cover; refrigerate until serving time.
Just before serving, pour dressing over salad; stir gently to coat. Top with feta cheese.