This recipe for chips, a perfect complement to Battered Cod, comes courtesy of chef Cathal Armstrong.
Cut potatoes lengthwise into 1/4-inch-thick slices. Then cut each slice lengthwise into 1/4-inch strips.
Fill a large saucepan with enough oil to reach a depth of 5 inches. Heat over medium-high heat until it reaches 285 degrees on a deep-fry thermometer. Working in batches, add potatoes and cook 10 minutes. Using a slotted spoon, transfer potatoes to a parchment-lined baking sheet. Cool to room temperature and transfer to a refrigerator until chilled.
Reheat oil over medium-high heat until it reaches 350 degrees on a deep-fry thermometer. Return potatoes to oil and cook until golden brown. Transfer to a paper-towel-lined plate and season with salt and vinegar; serve immediately.