One of my favourite breakfasts is toasted potato cakes but the ones sold in supermarkets are pretty tasteless so I make my own. They are easy to do and freeze well so I usually make up a big batch. You can also make just a couple by using up any leftover mashed potato.
Whether you use leftovers or make fresh mash specifically for the purpose the first thing you need to do is weigh them
You then need to add a quarter of that weight in self-raising flour. I had 696g of potato so added 175g flour.
The main thing to remember is to use COLD mashed potatoes because adding flour to hot ones makes the potato cakes very doughy. If you added salt to the potato cooking water there is no need to add any more, if not you'll need to add half a teaspoonful now.
Mix the flour into the potato until it all comes together
I use floured silicone paper so the dough doesn't stick to the work top and press it out until it's the thickness of a pound coin. You could use a rolling pin but it isn't really necessary. I used to cut out circles of dough, re-rolling the trimmings to get the most out of the dough, but nowadays I just make large ones and score them into sections. The amount of dough I had was enough to make 2 large potato cakes.
You can cook the potato cakes in a flat bottomed frying pan or on a griddle iron but I use my chapati pan.
Whatever type of pan you decide to use you need to pre-heat it until you can just hold your hand about an inch above the surface and feel the heat.
Cook the potato cake in the dry pan, don't add and fat, for about 5 minutes and then carefully turn over. I slide it onto a plate and then tip the uncooked side back onto the pan and give it another 5 minutes.
Cool the finished cake on a cooling rack and then cut into individual portions. They freeze really well and are lovely served toasted with a bit of butter or fried and served with bacon and egg.