01 -
Combine mayonnaise, sour cream, ketchup, pickle relish, lemon juice, and grated horseradish in a bowl. Season with kosher salt and freshly ground black pepper to taste. Set aside.
02 -
Heat corned beef in a skillet over medium-low heat with 10 ml water or broth, stirring occasionally until warmed through. Remove from heat.
03 -
Butter one side of each bread slice. Place two slices butter side down on a work surface. Spread Russian dressing over bread. Layer warm corned beef, Swiss cheese slices, and drained sauerkraut. Top with remaining bread slices, butter side out.
04 -
Heat a large skillet over medium-low heat. Place sandwiches in skillet, cover, and cook about 3 minutes until bottom is golden brown. Flip sandwiches and cook uncovered until the other side is golden and cheese is melted.