Dice the potatoes, onions and corned beef into similarly sized pieces.
Heat olive oil in butter in a large skillet over medium heat. Once butter melts add potatoes and cook 5 minutes without stirring.
Add in onions, garlic powder and pepper. Stir. Cover and cook for 2 - 3 minutes.
Uncover add corned beef and cook until the corned beef is warmed through. Add in green onions and season to taste with salt and pepper.
OPTIONAL: In a non-stick skillet, melt 2 tablespoons butter over medium heat. Once melted add egg. Allow to cook until the egg whites are set. Spoon hash onto a plate, top with fried egg and serve.
Notes
You can leave the peel on the potatoes if you prefer. Allowing the potatoes to cook untouched for 5 minutes helps them to get crispy. I also like to use a well seasoned cast iron skillet for this. It helps get a great crust on the potatoes. Nutrition information is for estimation purposes only.