Begin by preheating your oven to 400 degrees. Poke the top of each potato with a fork and place on a baking sheet. Cook in the oven for 1 hour. Once cooked, remove from the baking sheet, and place on a plate to let cool for about 15 minutes.
Once your potatoes are cooled, use a sharp bread knife and you will cut lengthwise. Be gentle and scoop out the potato, leaving a bit so the skin holds up. You still want some potato in the shell.
Brush the interior and exterior of each potato skin with the melted butter. Season the inside of each skin with salt and pepper.
Place them under the broiler for 8-10 minutes until the insides get a bit crispy from the melted butter.
Remove them from the oven and prepare everything for the next step.
Get two skillets out and preheated on the stove over medium heat.
To one, add the corned beef. I like a bit of that crispy edge of the corned beef. Cook the corned beef for about 4-5 minutes on medium heat until you get that slight crispness on the beef.
To the other skillet, add the sauerkraut, and the reserved cooking liquid from the corned beef. Cook on medium heat until the sauerkraut comes to a simmer.
It's time to prepare the potato skins.
If you are using Swiss cheese, add it to the bottom of each potato skin, and place back under the broiler for a couple of minutes, then remove from underneath the broiler.
Top each skin with the crispy, shredded corned beef. Add a bit of sauerkraut to the top, and drizzle with the remoulade.