Preheat oven to 200°C/180°C fan-forced. Place potatoes in a large, heatproof, microwave-safe dish. Cover with plastic wrap. Microwave on high (100%) for 3 to 4 minutes or until just tender. Drain. Pat dry with paper towel. Transfer to a bowl.

Add oil, sea salt and rosemary. Season with pepper. Toss to coat. Arrange potatoes, in a single layer, in a roasting pan.

Roast, turning, for 35 to 40 minutes or until potatoes are golden and crisp. Serve.