In a large, heavy-bottomed pot suitable for frying, heat the oil to 325F.
While the oil heats, slice the potatoes lengthwise 1/8 inch thick using a mandoline or very sharp knife.
Trim the square corners from either end of the strips of potato.

The result will be a long oval shape.
Place the potatoes into the oil, not more than two layers at a time. Overloading the pot will cause the temperature to drop.
In order to maintain a consistent temperature, move the potatoes constantly with a slotted spoon.
Cook the potatoes for 4 to 5 minutes, until light brown. Some will form small air bubbles. This is an indication that the meat of the potato has cooked away.
Once the potatoes have become inflated, remove them from the hot oil and set aside to cool until just prior to serving. 

To prepare this dish in advance, cook the potatoes until they puff, and immediately remove them from the 325F oil and lay flat on a sheet pan.
Place wax paper between the layers of potatoes.