Preheat the oven to 400 degrees. Preheat a large cast iron skillet in the oven.
Cut the smaller potatoes in half and the larger ones in quarters. Add to the preheated skillet. Toss with 2 tablespoons of oil and salt and pepper.
Roast for 20 minutes, stirring after 10 minutes. The potatoes should be fork-tender and caramelized around the edges. Cool slightly and transfer the potatoes to a plate. (Note 1)
Heat the same skillet over medium heat. Add one tablespoon of oil and the diced peppers and onions.
Cook, stirring occasionally, for 8-10 minutes until the peppers and onions are softened and starting to caramelize.
Add the corned beef and cook for another 8-10 minutes until the corned beef is starting to caramelize.
Stir in the potatoes and cook for another 3-4 minutes until warm. Season to taste with salt and pepper, if necessary.
Notes
Leftover roasted potatoes are ideal for this dish. Skip the potato roasting steps and start by cooking the peppers and onions.
A cast-iron skillet helps to create the caramelized edges which adds so much flavor to the hash.
Store leftovers in the refrigerator in an airtight container for 4-5 days.