French fried potatoes are fraught with misinformation. First off, they’re not French; they’re Belgian. Potatoes came to Europe via Spain (Pizarro), and Belgium was once part of the Spanish Netherlands (Charles V). Belgian—and French, for that matter—pommes frites are crisp outside, soft inside, sweetly browned and salty; in a word, perfect, because they are fried in two stages: once to cook the potato through, and again, at a higher temperature, to brown and crispen.
Use russets. Peel if you must, slice them on the thin side, rinse and drain thoroughly. Blanch in vegetable oil (peanut is better, tallow is best) at a simmering boil until soft, then drain and set aside. Turn up the heat under the oil. When the surface is shimmering, quickly add the potatoes in small batches; the oil will roil furiously and can easily boil over. When fries are buoyant and crisp, drain, salt, and serve.