Prepare the potatoes:
Cut potatoes into small uniform cubes (about 1/2 inch). Microwave them for 5 minutes to soften slightly.
Prepare other ingredients:
Dice the cooked corned beef into bite-sized pieces and finely chop the onion.
Heat the skillet:
Place a large cast-iron skillet over medium-high heat. Add butter or oil and let it get hot.
Cook potatoes & onions:
Add potatoes and onions to the skillet. Let them cook without stirring for 3–4 minutes until the bottom becomes crispy and golden.
Add corned beef:
Add diced corned beef. Stir gently and press everything down with a spatula.
Finish cooking:
Cook for another 8–10 minutes, stirring occasionally, until potatoes are crispy and golden.
Season & serve:
Add black pepper, paprika, garlic powder, and salt to taste. Garnish with fresh parsley or thyme and serve hot.