Use large potatoes such as Maris Piper so you get authentic long french fries with a fluffy interior.
• Soak the chopped fries in ice cold water for at least 30 minutes to remove excess starch and help them crisp.
• Dry the fries thoroughly with a tea towel after soaking to prevent soggy fries.
• Lay the fries in a single layer on the tray so they roast rather than steam.
• Flip the fries halfway through baking so they crisp evenly on all sides.
• Increase the oven temperature at the end for extra crispiness.
• Toss with parmesan while hot so it melts slightly and coats the fries well.