Cut the potato directly on to the pastry by cutting small flakes or dicing first, the choice is yours. Add a dot of butter and season well. Dampen the edges of the pastry and fold in half to form a semi-circle. Pinch and turn the edge over to make a rope like effect as shown in the picture above.
Some people jab a knife into the top to make a 'steam-hole'.
Brush on the beaten egg and place on a greased baking sheet. Eat, hot or cold, preferably by placing into a paper bag and eating from one end, turning the bag back as you go. Obviously, if you want to be posh you can put it on a plate and eat it with a knife and fork. Tradition is that the pasty shape represents the quarter moon with blunted horns. This is the emblem of Astarte, Goddess of the Phoenicians who came to Cornwall to trade tin.