Wash well, but do not peel the potatoes. Halve or quarter length-wise.
If only larger potatoes are available, cut into wedges. The pieces should be 1 to 1 1/4 inch thick. They should be uniform in size so the pieces cook evenly.
Heat the oil over medium heat in a large skillet. Place the potatoes, cut side down in the pan, cover, and cook on medium-low heat for 15 minutes. As each side becomes browned, turn the potatoes so all sides become brown and crusty. Add the rosemary. Potatoes are done when all sides are browned and the insides are soft, another 15-20 minutes after adding rosemay. Serve immediately.
Garnish with a little more fresh rosemary and salt, if desired.