Peel the potatoes if preferred (leaving skin on is optional). Cut each potato into 1/4"–3/8" thick sticks for classic restaurant fries. Rinse the cut fries in a large bowl of cold water, then drain and repeat until the water runs clear (about 2–3 rinses) to remove excess starch.

Soak

After rinsing, cover the cut potatoes with cold water and refrigerate or let sit for at least 30 minutes, up to 2 hours. This further removes starch and yields crisper fries.

Dry and toss with cornstarch

Drain the potatoes and pat completely dry with clean kitchen towels or paper towels. Transfer to a large bowl, sprinkle 2 tablespoons cornstarch over the fries, and toss until evenly coated. The cornstarch creates a light, crisp exterior.

First fry (blanch)

Heat 3 cups of oil in a heavy-bottomed pot or deep fryer to 300°F (150°C). Working in batches, fry the fries for 4–5 minutes until the centers are just tender and the exterior is pale and slightly cooked (no browning). Remove with a slotted spoon to a wire rack set over a tray and let rest for 10 minutes. Keep oil between batches at 300°F.

Final fry

Increase the oil temperature to 375°F (190°C). Fry the blanched fries in batches for 2–3 minutes or until golden brown and crisp. Drain on a wire rack or paper towel-lined tray. Immediately while hot, season with 1 1/2 teaspoons fine sea salt and 3/4 teaspoon coarse black pepper, tossing gently to distribute.

Truffle Aioli

Make the aioli while fries rest or in advance. In a small bowl, combine 1/2 cup mayonnaise, minced garlic (press or finely mince for a smooth texture), 1 teaspoon fresh lemon juice, 1/4 teaspoon Dijon mustard, 1/4 teaspoon fine sea salt, and a pinch (1/8 teaspoon) freshly ground black pepper. Whisk until smooth.

Add 1/2 teaspoon truffle oil, taste, and adjust: add up to another 1/4 teaspoon truffle oil if you prefer a stronger truffle aroma, or more lemon/salt to balance. Refrigerate the aioli for at least 10 minutes to let flavors meld. Bring to room temperature 10 minutes before serving if chilled.

Finishing & Serve

Transfer the hot fries to a serving bowl or platter. While still hot, sprinkle 1/2 cup finely grated Parmesan evenly over the fries so the cheese melts slightly into the fries.

Sprinkle 2 tablespoons finely chopped fresh parsley over the fries and finish with 1/2 teaspoon flaky sea salt if desired for texture. Toss gently to distribute garnish without crushing fries.

Serve immediately with the truffle aioli on the side for dipping. Provide extra truffle oil to pass at the table if desired.