Peel the potato, then cut it first into 1 cm (½ in) thick slices, then into wave-shaped strips about the size of French fries. If you use crinkle-cut fries then skip this step. Heat the oil in a large saucepan. To check the oil is hot enough for deep-frying, hold a wooden chopstick in the oil. If it is immediately surrounded by tiny bubbles, the oil is ready to use. Deep-fry the potato strips until golden and crispy, then remove and place on a piece of paper towel to drain. Put the potato strips in a big bowl and add the remaining ingredients. Mix everything together well.