Beat potato with wooden spoon until there are no lumps, or press through fine sieve. Add salt and rye flour, kneading to form sticky dough. Break off pieces of dough and roll out as thinly as possible. (You will need to use plenty of rye flour for this as the dough will be very sticky.) Cut into shapes; prick all over with fork. Heat heavy-based frying pan or griddle. Grease lightly with oil and kitchen paper and cook quickly on both sides. Best eaten fresh. (Easiest way to move from worktop to pan is by spatula.)
Choose a potato that will mash easily. Anyone who enjoys potato crisps will like these giant crisps. Use instead of crispbreads.