Wash the potatoes under cold running water to remove any remaining dirt. Then dry them well with a kitchen cloth.
Peel the potatoes and slice them in long rectangles, trying to model them like sticks, of the same size.
Cut them 8 mm thick and plunge them into a bowl with cold water leaving them to soak for at least 30 minutes.
After the 30 minutes pour the frying oil in a large pan and when the oil gets hot place the potatoes slowly after you have removed them from the water, place enough potatoes to cover the pan's surface and when the potatoes start getting a nice golden color, flip them on their other uncooked side.
When all the potatoes are cooked, remove them and place them on a plate with a kitchen paper on it, repeat the process until you fry all the potatoes.