Using a mandoline or sharp knife, thinly slice the potatoes. Put the potatoes in a large bowl of ice water and refrigerate for 1 hour. Meanwhile, in a deep heavy-bottomed pot, add the rosemary and enough oil to come 1/3 of the way up the sides. Heat the oil to 360 degrees F. Remove and the rosemary from the oil when it turns golden and crispy. Reserve.
Strain the potatoes and thoroughly pat dry by laying them out on a flat surface. Add potatoes to oil, in batches, making sure to keep the temperature above 350 degrees F. Fry until golden, about 3 minutes. While potatoes are frying, remove the rosemary leaves from stem and chop. Transfer the chips to a paper towel-lined bowl and sprinkle immediately with the rosemary and salt, to taste. Yield: 4 servings Prep Time: 15 minutes