2 large baking potatoes, peeled if desired I used purple potatoes
1. Pour enough oil to reach a depth of 2 3/4 inches in a deep fryer or a large, deep pot. Do not overfill the fryer or pot as the oil will bubble up when the potatoes are added. Heat the oil to 325°F (163°C). Line a baking sheet with a paper bag cut open or with a wire cooling rack and place it next to the stove.
2. Meanwhile, set up a turning vegetable slicer with the straight blade. Cut off both ends of a large baking potato and attach one end of the potato to the grip at the end of the handle; the other end of the potato should sit flush against the blade. Turn the handle, pushing toward the potato with gentle pressure. The potato will rotate through the blade, forming extremely long ribbons of potato.
3. Place the potatoes on paper towels and pat dry; they should be very, incontrovertibly dry before they go into the hot oil, as any residual moisture will cause the oil to bubble up and spatter even more.
4. Carefully add some of the potato ribbons to the hot oil, working in batches. Add only enough potatoes to make a layer that is no more than 2 inches thick. Fry the potatoes until they are golden brown on the bottom. Using long tongs, gently turn the potatoes over. Continue to fry until the potatoes are evenly browned and crisp, about 6 minutes total, depending on the thickness of your ribbons.
5. When the potatoes ruffles are done, use tongs to carefully lift them onto the paper bag or rack to drain. Serve the ruffles on a platter with a generous sprinkling of fleur de sel.