This is about as easy as you can get - cook this in batches and keep it warm in dishes covered with aluminium foil in a low oven.
Melt the butter in frying pans until foaming and gently fry the onions for 2-3 minutes, or until softened.
Add the potatoes and the corned beef and fry for 5-6 minutes, pressing down the mixture every so often with a fish slice, until the mixture is golden-brown and crisp.
When the corned beef hash is cooked, remove the pan from the heat, sprinkle over the Worcestershire sauce and parsley and season to taste with salt and freshly ground black pepper.
