Preheat oven to 450℉. Line 2 baking sheets with parchment paper.
Cut potatoes into 1/4 inch strips using a mandoline slicer or knife. Place the potatoes in a large bowl of cold water for 20 to 30 minutes, changing out the water halfway through. This will help remove the starch in the potatoes and make your fries crispier. Drain and thoroughly dry the potatoes with a kitchen towel.
Divide the fries among the two baking sheets, drizzle with oil and sprinkle with salt and pepper. Toss to evenly coat. Spread the fries out so they are in one even layer so they can get nice and crispy.
Bake both pans at once for 35 to 40 minutes, swapping pan position halfway through. Bake until golden and crisp. For extra crispiness, toss fries and broil 1 to 2 minutes at the end. Serve with ketchup or dipping sauce of choice.