We like our potatoes roasted: parboil them with the skins on, then drain, transfer to an oven tray and baste with oil.
The problem was that we couldn’t get them really crispy. Then in a conversation with my brother all became clear.
The best potatoes for roasting are floury ones (floury potatoes tend to turn to mush faster when overcooked), but the potatoes available locally are not particularly floury. The solution: after draining put some flour in the pan and tumble the potatoes in it. Then deposit the floury potatoes in the oven tray, baste with oil and nuke them at a high temperature.