Whether you cut your fries into sticks or wedges, the pieces need to be the same size. This ensures that the fries cook at the same rate. Remember: you’re cooking at 450 degrees F—that’s high heat. If you cut the pieces too big, they’ll be overdone on the outside and underdone on the inside. If you’re going for the classic “fry” shape, 1/4-inch-thick matchstick slices work. A medium sweet potato cut lengthwise into 8 wedges works well too.