- Preheat oven to 200C
- Peel and slice potatoes into even, bite-sized pieces
- Fill a large saucepan with cold water, salt generously, add potatoes and bring to the boil. Reduce to a simmer and cook until potatoes are just tender in the middle when checked with a metal skewer or fork.
- Remove saucepan from heat and drain through a colander until liquid has evaporated.
- Return the potatoes to the dry saucepan over low heat and add duck fat and generous seasoning. Place lid on the saucepan and shake vigorously to coat the potatoes with fat.
- Transfer the potatoes to a roasting tray in one layer. Roast for 40 minutes or until golden.
Transfer to serving dish. Garnish with rosemary sprigs to serve.