Step 1

Make Thousand Island dressing: Stir together mayonnaise, ketchup, pickle relish, mustard, and onion powder in a small bowl.

Step 2

Arrange bread in a single layer on a work surface. Evenly spread as much Thousand Island dressing as you’d like onto 1 side of each bread slice. Top each slice of bread with cheese.

Step 3

Spread 1/4 cup sauerkraut onto each of 4 bread slices. Cover sauerkraut evenly with corned beef. Top with the remaining bread slices, cheese sides in. Butter the top slices of bread, using half the butter.

Step 4

Heat a large frying pan over medium-low heat until a drop of water sizzles immediately. Add 2 of the sandwiches, buttered sides down. Cook until bread is toasted on the underside, about 4 minutes, covering with a lid to help the cheese start to melt. Butter top slices of bread, using half the remaining butter. Flip sandwiches over and cook, covered, until bread is toasted on the second side and the cheese is melted, about 4 more minutes.

Step 5

Transfer sandwiches to a cooling rack so they won’t get soggy and repeat to cook remaining sandwiches, using the rest of the butter. Serve immediately, with any extra Thousand Island dressing and more sauerkraut if you like. (Tip: Don’t leave sandwiches covered in the frying pan, as moisture from condensation will make the bread soggy.)