Sailor Sandwich

Preheat oven to 200°F. Place a rimmed baking sheet on oven rack. Gather all ingredients.

Divide pastrami into 4 (4-ounce each) portions. Split each sausage lengthwise, without cutting completely through, so sausages remain attached along one long side.

Melt 1 tablespoon of the butter in a 12-inch high-sided skillet over medium. Add pastrami portions, and cook, covered, until lightly browned on bottom, about 2 minutes. Flip pastrami portions, and cook until heated through and browned, about 2 minutes more. Transfer to a large plate; do not wipe skillet clean.

Melt 1 tablespoon of the butter in skillet over medium. Add knockwurst, cut side down, and cook, covered, until browned, 1 to 2 minutes. Turn sausages, and cook, undisturbed, until heated through and browned on second side, about 2 minutes. Transfer to plate with pastrami; wipe skillet clean.

Spread 1 1/2 teaspoons mustard evenly on 1 side of each bread slice. Place 1 Swiss cheese slice on the mustard side of 4 bread slices. Top evenly with reserved pastrami portions. Place 1 reserved knockwurst over pastrami on each sandwich. Top evenly with remaining Swiss cheese slices. Close sandwiches with remaining bread slices, mustard-side down.

Melt 2 tablespoons of the butter in cleaned skillet over medium. Add 2 sandwiches, and cook, covered, until golden on bottom, 2 to 3 minutes. Flip sandwiches, and cook, covered, until golden on second side and cheese is melted, 1 to 2 minutes more. Transfer sandwiches to baking sheet in oven to keep warm. Wipe skillet clean and repeat with remaining 2 tablespoons butter and remaining 2 sandwiches. Serve immediately.