If you are starting with hot corned beef, slice it now. If not, heat sliced (leftover or deli) corned beef either (1) wrapped in foil in a 350°F oven or toaster oven or (2) in a lidded container in in the microwave with a tablespoon of water until warmed through.

Warm a cast iron skillet over medium heat.

Melt 1 teaspoon of the butter.

Place drained sauerkraut onto skillet and cook until warmed through. If little bits of it get caramelized, that's a nice bonus. Remove from skillet and set aside.

Spread one side of each slice of bread with the remaining butter.

Place bread buttered-side down on the skillet.

Spread the top face of each slice with half of the dressing. Top each with a slice of cheese.

Brown the bread while letting the cheese melt, adjusting heat as necessary so both processes happen in the same timeframe.

Layer on the warm corned beef and sauerkraut.

Close sandwich, cut in half if you like, and serve right away.

If you're making more than two or three sandwiches at a time, it helps to use the oven. By changing up the order of things a little bit, you can have all the sandwiches ready at once.

Preheat oven to 350°F.

If you're not starting with hot corned beef, wrap it in foil and pop it onto one side of a large rimmed baking sheet to heat for 10 to 15 minutes, until warmed through.

Meanwhile, warm a cast iron skillet over medium heat.

Spread one side of each slice of bread with butter.

Place bread buttered-side down on the skillet.

As each buttered bread slice comes off the griddle, pop it onto the baking sheet buttered-side down. You can spread on the dressing and layer on the cheese right before putting each slice into the oven, rather than doing it on the griddle.

Fry up the sauerkraut after all the bread is done.

Once all elements are hot, you can pull the baking sheet out of the oven and assemble the sandwiches.