4 lbs. small russet potatoes, or larger ones, cut in half
About 2 quarts peanut or vegetable oil for deep frying

Bring a large pot of salted water to a boil. Add the potatoes and boil for 5 minutes. Drain and let cool.

Pierce the potatoes with a fork all over. Place them in a heavy, wide-bottomed pot and add oil to cover. Heat oil over medium-high heat, then cook (do not stir) until tiny bubbles appear on the potatoes, about 15 minutes. Reduce the heat to medium-low and let the potatoes continue to cook, stirring occasionally, until they are medium-gold, about 2 hours. (At this point, the heat can be turned off and the potatoes can remain in the oil until ready to serve, up to 3 hours.)

Just before serving, turn the heat to medium-high and fry the potatoes until they are very crsip and golden brown, about 15 minutes. Use a slotted spoon to remove the potatoes and drain on paper towels. Serve immediately.