Set the hash browns out the thaw. Then cut the corned beef into 1/2-inch cubes.
For the Horseradish Cream Sauce:
Place all the ingredients in a medium bowl. Add 1/4 teaspoon of salt and 1/4 teaspoon pepper. Whisk until smooth. Cover and refrigerate until ready to use.
For the Corned Beef Hash:
Place a large 12- to 14-inch skillet over medium-high heat. Add 1 tablespoon of butter and 1 tablespoon of oil to the skillet. Add the corned beef and saute for 5-8 minutes, turning regularly, until edges are slightly crispy.
Remove the corned beef with a slotted spoon. Then add the onion and saute for 2 minutes. Add the remaining oil and butter and potatoes. Salt and pepper generously. Saute for another 10-14 minutes until the potatoes are brown around the edges and cooked through. Stir regularly.
Spoon the corned beef back into the skillet and toss.
Serve warm with Horseradish Cream Sauce drizzled over the top and eggs cooked to order on the side.