Pour the oil in a metal or cast iron baking dish and place in the oven. Crank up your oven to as high as it will go.

Boil a large pot of water. Peel and cut the potatoes into large pieces, about 6cm/2.2" wide.

Boil the potatoes for 10 minutes. Drain then return to the pot.

Scatter over the semolina and salt. Clamp the lid on and give the pot 5 good shakes to rough up the potatoes. Leave the lid on and set aside.

The oil should be hot enough by the time the oven comes to temperature. Test it by tossing in a pinch of potato - it should sizzle straight away.

Pour the potatoes in (be careful of oil splashing). Working quickly, use an egg flip to toss the potatoes in the oil, spread them out as best you can then put the pan to the oven.

Turn the oven down to 220C/425F. Roast for around 50 minutes, possibly up to 1 hr 15 minutes, turning once during baking.

They are ready when they are a golden brown with some browned edges and they are crunchy. Serve immediately!