Fill a large saucepan with water and bring to a boil over high heat. Fill a large bowl with cold water and a few scoops of ice, set aside.
Add the green beans to the boiling water and cook for 4-5 minutes until tender but still crispy; drain. Immediately plunge the green beans into the ice water bath. Allow the beans to chill for 5 minutes, drain well and pat dry.
In a small bowl or jar, whisk together the dressing ingredients.
Arrange the green beans on a serving platter. Drizzle with the dressing then top with the olives, sun-dried tomatoes, walnuts, and lemon zest. Refrigerate until ready to serve.
Omit the walnuts, or replace with pistachios or toasted almonds.
Add fresh sliced small tomatoes to the platter with the green beans, before drizzling with vinaigrette.
Top salad with feta cheese or shaved Parmesan, if desired.
Make Ahead: Blanch the green beans, arrange them on a platter, cover with plastic wrap, and refrigerate for up to one day or overnight. Prepare vinaigrette and refrigerate. Toast walnuts, cool completely, and store in covered container.