The best breakfast anywhere on Earth. I might be biased.
A cast-iron skillet is best for the good heat holding ability and a good crust.
Melt the fat or butter in the skillet on medium heat. Add the onions and let them start to brown. When you start to smell the onions, add the potatoes and beef. Mix everything together well and let the hash start to form a crust. Keep the pan on medium heat.
Jostle the pan to loosen the hash from the pan. You may need to encourage it to release with a metal spatula and some more butter. As it cooks it should develop a crust and this will help it remain free from sticking.
As the hash forms a crust and releases, season the top with salt and pepper. When a good crust has formed, slice the spatula under the hash and flip it over. This is a bit trickier than it seems but if parts don’t play nicely, turn those over as well.
Jostle the pan again to make sure nothing is sticking or starting to burn.
When the has the beginnings of a crust on the new bottom, add a few pats of butter to ensure it stays released.
When hot in the middle, portion on plates and serve with eggs or more hash.