Wash, peel and remove any black spots from the potatoes. Cut the potatoes into even sizes, ensuring there are straight edges and right angles. This is easier to achieve with large potatoes

Place the potatoes in a large pan and cover with cold water. Season the water well. It should taste like the sea. Bring the potatoes to a slow boil. Cook until they are nearly cooked and then drain the water

Once drained, place the potatoes back in the pan, put the lid on and then shake firmly, so that they start to break up on the outside, not all the way through

Place a heavy based roasting tray over two hob rings, add the duck fat and melt. Put the potatoes in the tray and turn over with a fish slice. You are looking to achieve a golden crisp colour on the potatoes. The colour does not need to be even all over

Once the potatoes have a good amount of colour and before they start to burn place them in a hot oven on 220ºC/Gas mark 8 and roast until golden all over. When ready to serve, sprinkle with chopped sage and marjoram