Preheat the oven to 220C/425F
Cut the potatoes into chunky pieces that are a bit larger than a pingpong ball (approx. 2 inches/5 cm).
Cover with cold water and place in a saucepan. Place in a pan and cover with cold water.
Place the lard (or any other fat you prefer) in a large baking tin. Bake for 10 minutes or until the butter is melted.
To roughen the edges, drain the potatoes in a colander If a few potatoes break apart or appear too fluffy, don't be discouraged. They will absorb fat better and be crispier if they are more fluffy.
Place the potatoes in the baking tray with the hot fat. Turn the potatoes over to coat with the fat. Then, bake in the oven.
Cook for between 30-35 minutes. Turn once or twice during the last 15 minutes to make sure it is crispy and golden brown.
Take the roasting pan out of the oven and sprinkle with Maldon salt.