The potatoes are peeled and dried with a clean tea towel.
Now cut grooves into the potatoes. It is easy to cut the many grooves if the potatoes are placed in a wooden spoon while cutting. Use a sharp paring knife to cut slices about 2/3 into the potato - the closer the grooves are, the better. It's important not to cut all the way through the potato, as it would then fall apart.
Pour the oil into a small bowl and season with salt and pepper.
Turn the potatoes around in the oil.
Place the potatoes on a baking sheet lined with parchment paper.
Cook the potatoes in the oven at 200 degrees Celsius (392 degrees Fahrenheit) (conventional) or 180 degrees Celsius (356 degrees Fahrenheit) (fan) for 40 - 45 minutes.
Take the finished potatoes out of the oven and serve.