Step by Step method

1. Step 1.

   Melt butter in 12-inch nonstick skillet over medium heat. Add onion, 3/4 teaspoon salt, and 1/2 teaspoon pepper and cook, stirring frequently, until onion is translucent, about 3 minutes. Increase heat to medium-high; add potatoes, garlic, and water. Cover and cook for 6 minutes. Remove lid and continue to cook, stirring frequently, until potatoes are cooked through and no water remains in skillet, about 6 minutes longer.

2. Step 2.

   Remove skillet from heat and, using a spatula or wooden spoon, mash approximately one-eighth of the potatoes. Stir mashed potatoes into the potato pieces until lightly coated. Stir in the corned beef and hot sauce and toss until well combined. Press hash into an even layer. Return skillet to high heat and cook, without stirring, for 3 minutes. Carefully slide hash onto a large plate—invert hash onto second plate and, using spatula, slide hash back into skillet. Return hash to high heat and cook second side until browned and crisp around edges, about 3 minutes longer. Transfer to pa latter and serve, passing extra hot sauce.