Although you must cut the French fries right before you cook them the first time, the first frying can be done up to 3 hours before you cook the potatoes the final time to serve.

1.    Line a baking sheet with paper towels. Heat 3 inches of oil to 325 F in a 4-to 5 quart Dutch oven over medium heat or in a deep fryer.

2.    While the oil heats, slice the potatoes lengthwise into ½-inch-thick planks.  Stack the planks 2 or 3 high and cut them into ½-inch-wide fries. 

3.    Drop all the potatoes into the oil and swirl them with tongs. Fry until the middle of a fry is hot when tested and doesn't snap when broken in half, about 3 minutes.  The fries should not pick up much color at all-do not let them brown.  Using a wire-mesh skimmer, lift up the fries and drain over the pot, then transfer them to the lined baking sheet and allow them to cool completely at room temperature, at least 20 minutes (or up to 3 hours). Let the oil cool as well.

4.    When ready for the second frying, line a second baking sheet with paper towels. If you want to keep the first batch of French fries warm until they are all cooked, preheat the oven to 200 F.  Add additional oil as needed to come 3 inches up the sides of the Dutch over or deep fryer and heat to 375 F.

5.    Drop half the potatoes into the hot oil and swirl them with tongs. Fry until deep brown, a full 5minutes or so.  Transfer the fries to the lined baking sheet and sprinkle with salt.  You can serve them immediately or keep them warm in the preheated oven.  Fry the remaining potatoes, making sure to let the oil come back to 375 F before adding the second batch.   Drain on the lined baking sheet, sprinkle with salt, and serve hot with ketchup or cider vinegar.  I also like black pepper cracked over my fries.