Preheat the oven to 425°F. Prepare a baking pan by lining with foil and set aside.
Place a potato on a cutting board. Arrange chopsticks on either side of the potato as a guide; this will help keep you from slicing all the way through the potato.
Using a sharp paring knife, make thin, vertical slices into the potato, making sure to stop before reaching the bottom. Be careful on the ends as the chopsticks will not be able to guide you from slicing all the way through if they're not touching the ends. Make cuts anywhere from ¼ to ⅛ inch thick. Repeat with all potatoes.
Gently rinse each potato under cold running water, removing the starchy liquid from between the slices, then pat dry.
Place the potatoes on a microwave-safe plate and cover with a damp paper towel. Cook on high for 4-5 minutes, just until the potatoes are slightly softened.
Place the par-cooked potatoes on the prepared baking pan and brush each with olive oil or melted butter. Season each with about ¼ teaspoon of sea salt.
Bake for 30-40 minutes depending on the thickness of the potato, brushing with remaining olive oil or butter about half way through the bake time. Insert the tip of a knife a thick part of each potato to test for doneness; you'll want them to be tender in the center, but crisp and browned on the slices. Serve hot.