Heat 1 cup of oil in a large nonstick skillet over medium-high heat until shimmering.
While the oil heats, scrub and dry 2 large russet potatoes.
Using a mandoline slicer, carefully slice each potato lengthwise into 1/16-inch-thick pieces, discarding the top and bottom slices or saving them for another use.
Stack the slices in order to retain the original shape of the potato, then trim the edges to form a clean rectangle.
Place the offcuts in cold water for later use.
Cut the rectangle into three or four bite-sized stacks, repeating the process with the second potato.
Carefully place the potato stacks on their sides in the hot oil, ensuring they are close together but not touching.
Reduce heat to medium and cook for 4 to 5 minutes, adjusting the edges with a fork or spatula as needed, until the bottom and sides turn deep golden brown.
If available, use a splatter screen to prevent oil splashes.
Flip each stack away from you and cook for another 4 to 5 minutes until all sides are golden and crispy.
Transfer to a paper towel-lined plate and immediately season with flaky salt or preferred seasonings.
Serve hot and enjoy!