How to Make It
Preheat grill to medium-high heat (350° to 400°). Toss potatoes with 1/3 cup olive oil, salt, and pepper; grill 2 to 3 minutes or until potatoes are tender. Let cool slightly.
Whisk together vinegar and mustard in a medium bowl; gradually whisk in 2 cups extra virgin olive oil in a slow, steady stream. Whisk in green onions, parsley, and chives. Pour dressing over warm potatoes, tossing to coat.