Remove the skin from the potatoes. First slice lengthwise about 2 mm thick (ideal with a slicer), then cut into fine sticks. Immediately put them into cold water and soak them for a few minutes. This causes the maizena (corn starch) to be flushed out and the potatoes no longer stick together during baking.
Remove the potatoes from the water in portions and drain them very well on kitchen roll, then dry them.
Just before serving, bake the potato straw: Heat enough oil in a roaster or deep fryer and bake the potato sticks in batches for about a minute and a half, until they are golden and crispy.
Lift out and drain well. Transfer to a platter and keep warm, uncovered, in the hot stove until all the potatoes are baked. Season with salt just before serving.