Place the potatoes in one layer in a large saucepan and add the oil, butter, water and salt. Bring to a boil, cover and cook over high heat for about 8 minutes. Reduce the heat and continue cooking, covered, over low heat for about 10 minutes to brown the potatoes. Add the rosemary and cook, stirring occasionally, 2 to 3 minutes longer. Serve.
Servings 6
