|Evenly sized floury potatoes||2 Pound, scrubbed but unpeeled|
|Butter||3 Ounce (75 Grams)|
|Mild onion||1 Small, finely chopped|
Cook the potatoes in a large saucepan of lightly salted boiling water for about 7 minutes.
When the potatoes are quite cold, peel them and grate them coarsely into a bowl.
Heat 15 g (1/2 oz) of the butter in a large frying pan.
Add the onion and cook for about 5 minutes until it is soft.
Stir the onion into the grated potato and season to taste.
Melt the remaining butter in the frying pan.
Set aside about 1 tablespoon of the melted butter in a cup.
Add the potato mixture to the pan and form it into a neat cake.
Cook gently for about 15 minutes, shaking the pan occasionally so that the rosti cake does not stick, until the underside of the cake is a crusty golden-brown.
To cook the top of the rosti, pour over the reserved melted butter and either place the frying pan under a preheated grill to brown or turn the rosti over in the pan and brown.
To serve invert the rosti cake on a warmed flat dish and cut it into wedges.