Place the oil in a large, deep, pan, Dutch oven, or deep fryer. Attach a deep-fry thermometer to monitor the temperature and heat oil to 350°F.
Canola oil
While the oil is heating, wash and peel the potatoes and remove any dark spots.
4 large Russet potatoes
Using a mandoline slicer fitted with the julienne blade, slice potatoes into matchsticks.
Place the sliced potatoes in a large bowl of ice water and chill for 10 minutes.
Remove the potatoes from the water bath and place them on paper towels or clean dishcloths to dry completely. Pat the potatoes dry or use a salad spinner, if available. The dryer the potatoes, the less excess splattering there will be.
Once the oil is 350°F, place the dried potatoes (1 cup at a time) in the oil and stir to separate them. Adjust the temperature to keep it as close to 350°F as possible. To avoid oil flare-ups, DO NOT add too many potatoes at one time.
Fry 2½ - 3½ minutes or until dark golden brown. Watch closely and stir often.
Transfer cooked potatoes with a slotted spoon to a paper-towel-covered surface and season with salt and black pepper. If desired, add other spices or seasonings at this time.
Kosher salt and freshly ground black pepper
Repeat the process until all potatoes are fried.
Serve as is or with the dip of your choice.