Fill a large pot with water, then add 1/2 teaspoon of salt.: The kitchen will smell faintly of minerals as the water comes to a gentle boil, and this salted water is the first flavoring step for the potatoes . The salt in the water seasons the interior as it cooks, ensuring every bite has depth. A common mistake is under salting the water, resulting in bland centers. If the pot seems crowded the temperature will drop and the boil will take longer, so use a pot large enough to keep a rolling simmer.
Peel the potatoes and cut them into large, bite-sized chunks.: You will feel the firmness of the potatoes as you work, and uniform pieces help them cook evenly. Large chunks preserve a fluffy center while still allowing edges to crisp. Avoid pieces that are wildly different in size, as small lumps will overcook and fall apart while larger chunks remain underdone.
Add the potatoes to the cold water, then bring to the boil. Boil for 10 minutes, and meanwhile, preheat the oven to 425°F and place a roasting pan with oil inside to heat.: Starting in cold water helps them heat through evenly, producing a creamy interior. As the water warms you will see tiny bubbles form, then a full boil, which signals that the starches are loosening. Boil for 10 minutes to reach parboil stage without collapsing the structure. Over boiling is a trap that makes the potatoes soggy and unable to crisp well later.
Drain and rough up the potatoes in a colander to create a textured surface for extra crunch.: When you shake the potatoes in the colander you will hear a tumbling noise and see the edges break open slightly, creating that sought after rough exterior. Those ragged bits are what become golden and crisp in the oven. Be careful not to press too hard, or you will mash the pieces instead of texturing them.
Carefully add the potatoes to the hot oil in the roasting pan, ensuring they are spaced apart. Roast in the oven, turning every 15 minutes, until golden brown and crispy, about 60 minutes total. Season with the remaining salt and pepper before serving.: A confident sizzle will greet each piece, and that immediate sound is a good sign the oil is properly hot to start browning. Spacing is crucial, crowding will trap steam and prevent crisping. Use long tongs and protective mitts when placing them, and avoid dumping the whole colander in at once which could cool the pan dramatically.
Roast in the oven turning every 15 minutes until golden brown and crispy about 60 minutes total: Visual cues are your guide here, watch for a deepening golden color and listen for a sustained faint crackle as the crust forms, that means the Maillard reaction is working. Turning regularly promotes even browning on all sides. One common oversight is impatience, checking too often lowers the oven heat and slows caramelization, so turn efficiently but not excessively.
Season with the remaining salt and pepper before serving: After roasting, the surface will be hot and the aroma of baked starch will rise, and this is the ideal time to season. The finishing salt and black pepper boost the flavor and keep the seasoning bright. Avoid over seasoning early on, because once the crust forms the seasoning will concentrate; taste a small piece first to calibrate.