When you are ready to eat, line a medium-size bowl with several layers of paper towels. Crank up the heat under the oil (the same oil if you’re continuing right away, fresh oil if you had frozen the potatoes) until the thermometer registers at 400°F. Carefully drop one-quarter of the chilled (or frozen) fries into the oil. The temperature will drop to around 375°F. Make sure the heat under the pan is adjusted to maintain this temperature. As soon as the fries are caramel brown and crispy, 2 to 3 minutes, fish them out of the hot oil with a slotted spoon and drop them into the paper towel-lined bowl. Toss them gently to remove excess oil. Sprinkle the salt and peppercorns over them, toss again. Repeat frying, draining, sprinkling, and serving the remaining potatoes in 3 more batches. No, do not wait to serve them until all of them are fried. They are best as soon as you sprinkle them with salt and pepper.