Pre-heat the oven to 400°F.
In a large saucepan, combine vinegar, potatoes and water.
Bring to a boil; then reduce heat and simmer for 10 – 15 minutes or until potatoes are tender.
Drain well and cool for 10 minutes to dry slightly.
While potatoes are boiling using a small bowl, combine rosemary and salt flakes; set aside.
Toss potatoes with oil and ½ of the salt and rosemary mixture until well coated.
Line a large baking sheet with parchment paper.
Place potatoes in a single layer on tray.
Place in the pre-heated oven and roast for 30-35 minutes, turning halfway through cooking time, until golden and crispy.
Scatter with remaining salt mixture; serve.
