Heat butter in a large skillet (preferably cast iron) on medium heat. Add chopped onion and sauté for a few minutes, until translucent. Add a pinch of red pepper flakes.
Add the quartered potatoes and chopped corned beef and spread evenly in the pan. Increase the heat to high and press down on the mixture with a metal spatula.
Sizzle and brown the mixture without disturbing for about 5 to 10 minutes, checking the bottom to see if nicely browned. Add a bit more butter if sticking.
Once browned, flip has to brown on other side, another 5 minutes.
Reduce heat to medium. Make a well in the center of the pan and crack one or two eggs in center. Allow whites to set then cover and remove pan from heat.
Allow eggs to cook around 5 minutes for sunny side up.
Season with a dash of salt and freshly ground pepper.
Garnish with chopped parsley and serve with a slice of toasted sourdough or griddled Irish soda bread. Enjoy!