You can get a plate of corned beef hash and eggs for breakfast at just about any diner in town. Some places pride themselves on featuring fresh corned beef in their hash, other places jazz up the recipe with the addition of fresh herbs or heavy cream. Even Worcestershire sauce has found it's way into some recipes I've come across. Technically speaking, hash is any dish made up of ingredients that are diced up finely and fried together in a pan so there's quite a lot of leeway when it comes to what constitutes a hash.
My preference when it comes to making corned beef hash is to keep it as simple as possible. I stick to just three ingredients; a can of corned beef, diced onion and potatoes. You can fry it all up loose and sloppy or make them into patties like I do.
In Hawaii, at local okazuya's or old-fashioned Japanese style deli's, you can always find corned beef hash patties ready for your bento box. Often, at these places, the ratio of potato to corned beef is heavy on the potato side of things but if you make your own, you can ensure you get a healthy serving of corned beef in every bite.
To one can of corned beef, I add a diced onion and two medium sized russet potatoes that have been peeled, sliced, cooked and roughly mashed. Mix everything up to incorporate, divide the mixture and roll into balls then pat them down into patties. Stick them in the refrigerator to cool while you heat up a large pan. When the pan is good and hot, pour in about a 1/4 inch of vegetable oil. When the oil begins to ripple, add the patties to the pan and fry them until they form a crispy crust.