Peel the sweet potato. Adjust the fluted blade of a mandoline to 1/4 inch and with the mandoline slice the sweet potato, turning it a quarter turn after each slice to produce a waffle pattern. In a deep skillet heat 1 inch of the oil over moderately high heat to 375°F. on a deep-fat thermometer, in it fry the slices in batches, turning them, for 1 minute, or until they are golden, and transfer the chips as they are fried with a slotted spoon to paper towels to drain. The chips may be made 1 day in advance and kept in an airtight container. Just before serving arrange the chips in one layer in shallow baking pans and heat them in a preheated 400°F. oven for 5 minutes. Sprinkle the chips with salt to taste and serve them warm.
