Peel, quarter and place the potatoes into a large pan of cold water. Add salt and bicarbonate of soda. Bring to the boil and par boil (10-15 minutes), they should be almost soft enough to turn into mash. Gently drain them and allow the water to steam off. Place them onto separate tray to cool and fully steam dry, this allows them to firm up and the jagged edges to appear, which will result in a crisper finished product.