Cut potatoes ¼-inch slices, then cut each slice into ¼-inch strips. This should leave you with fries that are the length of a Russet potato, and ¼x1/4-inch thick.
Fill a large bowl with cold water. Place potatoes into the bowl and refrigerate for at least an hour, or up to overnight.
After potatoes have soaked for at least an hour, remove from water and rinse well to remove the starch. Lay out on a towel and pat dry.
In a Dutch oven or deep fryer, heat oil to 275 degrees. Working in batches, fry potatoes for 5 minutes, then lay on paper towels or a wire rack to cool
Once all of your fries have been cooked, turn your burner up and heat oil to the 350-375 range. Keep an eye on your thermometer to ensure it stays within this range as you add and remove your potato batches. Adjust your heat, as needed.Once again working in batches, cook potatoes for 3-5 minutes, or until golden brown. Remove with a slotted scoop and season with salt while warm.
In a large bowl, place garlic, Parmesan cheese, and truffle oil. Add salted French fries and toss to coat.
If using truffle oil with synthetic additives the flavor will be much stronger. Reduce to 1 teaspoon and adjust to your taste preference.