Heat the oven to 450°F / 230°C with a heavy rimmed metal sheet pan on the middle rack. Put the potatoes in a pot, cover with cold water by an inch, add the salt and bring to a boil.
Reduce to a simmer and cook for 7–10 minutes, until the edges give when scraped with a fork but the centers still hold together. Drain and steam dry for 3 minutes.
Return the potatoes to the empty pot and shake gently to roughen the edges. Add the oil and toss until the shaggy surfaces are evenly coated.
Carefully spread the potatoes in a single layer on the hot pan. Roast for 20–25 minutes before turning; if they stick, give them a few more minutes to brown. Continue roasting for 15–25 minutes, until deeply golden and tender inside. Season and serve hot.