Put the potatoes in a large saucepan and cover with water. Add 1 teaspoon salt to the water. Bring to a boil over high heat, reduce to a simmer and cook the potatoes until they are very tender but not overcooked, about 10 minutes.
Remove the potatoes from the water and let them drain on a dishtowel, gently patting to dry. Allow to cool.
Gently press down on one potato with a spatula to gently flatten it to about 1/2 inch thick. Repeat, one potato at a time, until all the potatoes are flattened. Don’t worry if some break apart a bit; they are still fine to use.
Cover a large rimmed baking sheet with aluminum foil; this reduces cleanup. Transfer the flattened potatoes carefully to the baking sheet.
Heat the oven to 450°F Pour the olive oil over the potatoes and sprinkle with the remaining salt and a few grinds of black pepper. Lift the potatoes gently to make sure some of the oil goes underneath them and that they are well coated on both sides. Roast the potatoes, about 10 to 15 minutes, turning over once gently with a spatula. Continue to roast fingerlings for about another 10 minutes until they’re crispy and deep brown around the edges,. Remove from oven.
Drizzle each potato with a few drops of truffle oil and serve hot.