After a bit of trial and error, I realised that the key to this is to think of the potato and flour mixture as a dough, and to treat it accordingly. Also, you have to add plenty of flour during the shaping and rolling stage to prevent the scones from sticking.
500g of leftover mashed potato
100g of flour
- Gradually work the flour into the potato, gently kneading the dough until you have a good smooth dough. (The exact quantity of flour required will depend on how dry your mashed potato is, so best to add the flour gradually.)
- Flour a worksurface or board, put more flour on your hands, and take off a smallish ball of the mixture (somewhere between the size of a golfball and a satsuma).
- Press the ball so you have a fat disc, flour each side well then, using a well-floured rolling pin, gently roll it to a flat circle, about 1/2 cm thick, turning it between each roll and adding more flour to the worksurface or board if required.
- Heat a heavy-bottomed pan, grease with a little oil (but not too much), and then cook the scones on a low heat for about 3 minutes each side.