Sliced Roast Beef & Swiss Cheese Recipe

Prep vegetables and condiments

Thinly slice the red onion into rings (about 1/8-inch). Slice the tomato into 4 even slices. Rinse and pat dry the lettuce leaves. In a small bowl, stir together the mayonnaise and Dijon mustard until smooth; set aside.

Prepare rolls

Slice each sandwich roll horizontally, leaving a small hinge if you prefer. Spread about 1 teaspoon of the butter evenly on the cut inside of each top half (optional for flavor). Lightly butter the bottom halves if you like a richer bite.

Assemble roast beef and cheese

Divide the thinly sliced roast beef into four portions (about 3 oz each). Layer each bottom roll with 3 oz roast beef, arranging slices so they sit evenly. Place one Swiss cheese slice over the beef on each sandwich, folding the cheese if needed to cover the meat.

Season and add produce

Season the tomato slices lightly with the 1/4 teaspoon salt and 1/8 teaspoon black pepper. Place one tomato slice and one lettuce leaf on top of the cheese on each sandwich. Add a few red onion rings to taste (about 1 tablespoon per sandwich).

Add condiments and close

Spread about 1 teaspoon of the mayonnaise–Dijon mixture on the inside of each top roll. Close sandwiches and press gently to compact them slightly.

Toast or melt (optional)

For a warm sandwich and melted cheese: brush the external cut sides of each roll lightly with 1 teaspoon olive oil or melted butter. Place sandwiches on a baking sheet and toast under a broiler or in a 375°F (190°C) oven for 3–6 minutes, watching closely, until cheese is melted and bread is golden. Remove and let rest 1 minute before serving.

If serving cold, skip this step and serve immediately.