Preheat oven to 400° F.
Combine 1-½ tablespoons of the olive oil, ½ teaspoon salt, ¼ teaspoon pepper, garlic cloves, and potatoes on a large rimmed pan. (Cover pan with foil first, for easy clean-up!) Toss well to coat. Bake for 1 hour or until tender, stirring after 35 minutes. Keep an eye on the garlic - if it's soft before the potatoes are done, remove it to a plate and let the potatoes continue cooking. Once potatoes are completely tender, remove from oven and let cool for 5 to 10 minutes.
Squeeze garlic cloves to extract pulp. Discard skins. Combine garlic pulp, remaining 1-½ tablespoons oil, remaining ¾ teaspoon salt, remaining ¼ teaspoon pepper, chives, vinegar, and mustard in a large bowl; stir well with a whisk. Add potatoes to bowl; toss well to coat. Garnish with additional chopped fresh chives and some fresh cracked black pepper.
