Start by taking a 1/2 tablespoon of butter and heat it on a medium skillet on medium to high heat. Add in the olive oil and make sure the butter bubbles.
Crack your egg onto the heated butter and oil being careful not to break the yolk. Season with salt and pepper. You'll want to cook the egg over easy as it will continue to cook when we build the sandwich.
Butter one side of each slice of bread.
Add another skillet to the stove, and bring that to medium heat. Add one slice of the bread, butter side down, then add a slice of Swiss cheese. Top with the cooked corned beef, top with the cooked egg, then top with the cheese. Add the second slice of bread, butter side up.
Cook for a few minutes, then carefully lift and see if the bottom side is beginning to get nice and golden. Once nice and golden, carefully flip the sandwich over, and continue to cook until that side is nice and golden. Just be careful not to push down on the sandwich as you do not want to break the egg.
When you are ready to serve, simply place the sandwich on the plate and slice on the diagonal.
The end result is a perfect breakfast sandwich. Not only did Nueske's get it right, once again, with their corned beef hash, but the sandwich itself was awesome. The Swiss cheese is perfectly melted and that egg that oozes into the seasoned corned beef, well, need I say more?