grainy mustard aioli
1. Wash and peel the russet potatoes. Cut them into thin strips to form fries. Soak the fries in cold water for at least 30 minutes to remove excess starch, then drain and pat dry.
2. In a large pot or deep fryer, heat the vegetable oil to 350°F (175°C). Carefully add the fries in batches, frying until golden brown and crispy, about 5-7 minutes per batch. Remove the fries and drain on paper towels.
3. While the fries are still hot, drizzle with truffle oil, then sprinkle with Parmesan cheese, sea salt, and black pepper. Toss to combine.
4. In a bowl, whisk together the mayonnaise, grainy mustard, lemon juice, minced garlic, salt, and black pepper until smooth and well combined.
5. Serve the truffle Parmesan fries warm with the grainy mustard aioli on the side for dipping.