Prepare a medium fire in a charcoal grill or preheat a gas grill on medium. In a medium bowl, toss potatoes with olive oil until well coated.

Arrange potatoes around cool outer edges of grill or place on upper rack if grill is so equipped. Cover and grill potatoes until tender when pierced with a knife, about 20 minutes.

While potatoes are grilling, put green onions and bacon in a large bowl, and make dressing. Combine olive oil, vinegar, garlic, parsley, salt, sugar and pepper in a small bowl. Set aside.

When potatoes are tender, transfer to a cutting board and cool for 5 minutes. Cut potatoes in half and add to bacon and onions in the bowl. Stir dressing to combine and pour over potatoes. Gently toss to thoroughly combine. Serve immediately. (The potato salad can be made up to 2 hours prior to serving. Cover and set aside at room temperature.)