Peel the potatoes, leave small ones whole, halve medium ones and quarter large ones.  Put in pan, cover with water, add some salt and bring to boil.  Lower the heat and simmer for 5 minutes.  Drain and leave to cool completely.
Heat some oil in a pan, thinly slice onion and fry gently until soft. Grate the cheese. When the potato is completely cool, grate into a large bowl, add the onion, cheese and season well with salt and pepper. 
Heat some oil in a non-stick pan.  For handfuls of the potato mixture into rough patties.  Placed the patty on the hot pan and fry without moving for 5 minutes allowing a golden crust to form underneath.  Carefully flip it over.  Continue to cook turning once or twice more.  It should take 10-12 minutes in all. 
Serve as a side dish, or with a poached egg as a delicious supper dish.