Hello BritBaker88. It is a pleasure to help you refine your chip-making process for a healthier meal. To achieve that elusive crunch, the choice of potato is indeed paramount. Maris Piper or King Edward varieties are excellent choices because their high starch content leads to a fluffier interior and a crispier exterior when roasted.
To improve your results, I suggest the following:
1. After parboiling and shaking the potatoes, I recommend dusting them lightly with a tablespoon of cornflour or semolina. This absorbs excess moisture and creates a textured surface that crisps up beautifully in the oil.
2. Regarding the temperature, try increasing your oven to 220C (fan).
3. Position your tray on the top rack. This is typically the hottest part of the oven and will help brown the chips more effectively than the middle shelf. Ensuring you do not overcrowd the tray is also vital; if the chips are too close, they will steam rather than roast.
For more inspiration on achieving a healthy crunch with vegetables, you might enjoy reading this article: Fried eggplant in crispy breading (
https://www.itseaten.com/recipe/fried-eggplant-in-crispy-breading).