Turn the stove to high heat now. Bring the water to a rolling boil. Cook the potatoes until they are just tender.

Drain the potatoes using your colander. Let them steam dry for a few minutes. Dry potatoes crisp up much better.

Chop your onions and corned beef. Keep the pieces about the same size. This helps everything cook evenly in the pan.

Melt the butter in the large frying pan. Add the chopped onions to the hot butter. Sauté them until they are soft and clear.

Add the potatoes and corned beef to the pan. Press them down firmly with your spatula. This creates a wonderful crust on the bottom.

Drizzle the Worcestershire sauce over the mixture. Sprinkle with salt and pepper to taste. Mix it gently once then let it sit.

Cook on medium heat for ten minutes. Flip the hash in sections to brown the other side. Serve it hot with fresh parsley on top.