Put the potatoes in a large saucepan and cover with water. Add 2 tsp 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 15 to 20 minutes.
Place a double layer of clean dishtowels on your countertop or cutting board. Remove the potatoes from the water, and let them drain briefly on the dishtowels.
Fold another dishtowel into quarters, and using it as a cover, gently press down on one potato with the palm of your hand 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; put a sheet of parchment on top of the foil. Transfer the flattened potatoes carefully to the baking sheet and let them cool slightly.
Heat the oven to 450°F. Pour the olive oil over the potatoes and sprinkle with the remaining salt. 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 until they’re crispy and deep brown around the edges, about 20 to 30 minutes, turning over once gently with a spatula or tongs halfway through cooking.
Drizzle each potato with a few drops of truffle oil and serve hot.
Hints & tips:
For an extra burst of truffle flavor, substitute 1 tsp of truffle salt for part of the sea salt.
Make ahead options:
Boil and flatten the potatoes up to 8 hours ahead of time. Let potatoes cool completely, and store them on the pan, lightly covered, in the fridge. Then just bring them to room temperature, coat with oil and salt and roast at the last minute.