Wash the potatoes and cut them in chunky fries. I like to keep the skin on but you can also peel the potatoes before you cut them if you prefer
Boil a large pot of water with some salt and cook the fries till they are just cooked.
Take them from the water, drain in a colander and leave them to steam dry completely. They can't be wet so make sure they drain good and let all the steam go
place the fries on a large oven tray and toss with the olive oil. The fries may break a bit as this will give your really nice crunchy edges
Roast the fries in the oven on 220°c for 50-60min whilst turning occasionally
When the fries are golden and crunchy on all sides just sprinkle with some seasalt and they are ready to be served.