Spread 1 tablespoon butter evenly on the outside face of one slice of bread. If you prefer a lighter or oil-based toast, brush 1 teaspoon olive oil instead. Repeat for the second slice if you want both sides toasted (optional).

Layer sandwich fillings

On the inside (untoasted) face of the bread slice with mayonnaise, layer the ingredients in this order for best texture: 2 slices cheddar cheese, 4 slices salami overlapped to cover the bread, 2 slices tomato (if using), and 1 leaf of lettuce (if using). Place the mustard-spread bread slice on top, mustard-side down.

Toast or grill the sandwich (optional)

Heat a skillet or griddle over medium heat. Place the sandwich in the skillet, buttered side down. If you only buttered one side of each slice, place the buttered side down first. Cook 2–3 minutes until the bread is golden brown. Gently press with a spatula and flip; cook an additional 2–3 minutes until the second side is golden and the cheese is melted. If you prefer toasting in an oven, preheat broiler to high and toast on a baking sheet for about 1–2 minutes per side, watching closely to avoid burning.

Finish and season

Remove the sandwich from heat. Let it rest 1 minute, then slice diagonally or in half. Sprinkle freshly ground black pepper (about 1/4 to 1/2 teaspoon per sandwich) over the exposed filling or directly on the tomato if used. Serve immediately.