Peel the potatoes and cut them into chunks -if they are large cut them into 3 pieces with as many angles as you can. It is the number of angels that create the crispness. If they are smaller cut them in half slightly diagonally.

Put the spuds in a pot with and barely cover with water, add the salt and the lemon juice, and bring this to the boil. Once it has reached a rapid boil, turn the temperature down to a simmer and cook your potatoes for 5 minutes.

Drain in a colander and then return to the pot that they were cooked in and with the lid on, holding oven gloves or a tea towel shake the potatoes about so as to ruffle up the edges. I used a fork to further rough them up.

Stir through the duck fat which will immediately melt over the potatoes, and tip them into a large baking tray, making sure you don't overfill, there needs to be some space between the potatoes. If you add to many the steam will interfere with the browning of them. Scatter over a few sprigs of rosemary leaves, salt and pepper.

Roast for 1 1/4 hours or until they are at the desired crispy golden colour. I shook the pan around a few times and turned the spuds twice during the cooking time.

Scatter over more sea salt flakes and a few sprigs of rosemary as garnish and serve with your favourite roast.