Cut potatoes into French fry shapes, about 3/8-inch wide and thick, using a mandoline or a knife. Soak potatoes in a large bowl of cold water for about 30 minutes. Drain and pat potatoes dry with a clean towel.
Heat oil in a deep-fryer or deep saucepan to 275 degrees F (135 degrees C).
Gently lower 1/4 of the potatoes into the hot oil and cook, stirring occasionally, for 2 minutes. Transfer cooked potatoes to a clean towel using a slotted spoon. Repeat frying with remaining potatoes.
Heat the same oil to 350 degrees F (175 degrees C). Fry potatoes again, working in batches, until golden brown, about 5 minutes. Transfer fries to a clean kitchen towel using a slotted spoon.
Place fries in a bowl and drizzle truffle oil over warm fries; season with Parmesan cheese, parsley, and sea salt.
Most truffle oil is actually olive oil with truffle essence added. It will still lend a pleasing flavor to this dish and is about a quarter of the cost of infused truffle oil. If you can afford it though splurge a little and go for the real thing.
We have determined the nutritional value of oil for frying based on a retention value of 10% after cooking. Amount will vary depending on cooking time and temperature, ingredient density, and specific type of oil used.