Position an oven rack in the middle of the oven and preheat to 400°F.
Line a baking sheet with parchment paper and set it aside.
Peel the 4 medium russet potatoes, rinse them thoroughly, and pat them dry with a clean towel to remove excess moisture.
Using a mandoline slicer or a sharp knife, slice the potatoes into even rounds about 1/8 inch thick. Keep the slices as uniform as possible.
Arrange the potato slices in a single layer on the prepared baking sheet(s) so they do not overlap. Use more than one sheet if needed to keep a single layer.
Drizzle 2 teaspoons olive oil evenly over the arranged slices. Sprinkle 1/4 teaspoon salt and cracked pepper to taste over the slices, then gently turn or brush the slices so they are lightly and evenly coated.
Bake in the preheated oven for a total of 15–20 minutes, flipping each slice once about halfway through (after roughly 8–10 minutes), until the edges are golden brown and crispy.
Remove the baking sheet from the oven and let the potato slices cool slightly on the sheet for a few minutes before serving.