Preheat the oven to 230 degrees Celsius.

Wash and peel the potatoes. Cut in half and half again so you have large cubes. Season with salt & pepper and add a teaspoon of olive oil. Use your fingers to roughly combine.

Bring a pot of water to the boil, once boiling add a pinch of salt, the potatoes and drop the heat to a medium simmer. Cook for 8 minutes, 10 minutes maximum.

Get the duck fat and butter into the pan.

Meanwhile place the duck fat and the butter into a roasting pan and heat until the fat is shimmering hot, it must be very hot. Heat the oil for about 10 minutes.

Drain the potatoes in a colander, shake off any excess water, then tip them back into the pot and immediately put the lid on and give them a good shake to rough up the edges.

Carefully remove the pan from the oven and carefully place the par boiled potatoes into the oil using a pair of tongs or spoon. Working quickly but also carefully, turn them in the fat placing each cut side down,

Pour any remaining oil and seasoning over the potatoes.

Roast for 20 minutes without turning. After 20 minutes turn them in the oil once and back in the oven for another 10 to 15 minutes until golden brown.

Serve with fresh rosemary, thyme and sea salt.