Place the potatoes in a pot of cold salted water. Bring to the boil, then immediately reduce to a simmer. Simmer for about 10 minutes to par-cook then drain the water off. Leave to sit in the colander for a few minutes to ensure as much water has been drained as possible.
Place the oil in a baking tray and put in the oven for ten minutes. Remove and transfer par-boiled potatoes into hot oil/tray (use caution here as can splatter)