Tender roast beef with sharp cheddar on a crusty roll is a high protein, carnivore-approved deli favorite. This hearty sandwich makes a satisfying family lunch that's rich in flavor.
Preheat oven to 375°F. Slice each roll in half horizontally and spread the cut sides with unsalted butter.
Toast the buttered rolls, cut side up, on a baking sheet in the oven for 5–6 minutes until lightly golden.
Mix Dijon mustard and prepared horseradish in a small bowl, then spread the mixture evenly on the bottom halves of each toasted roll.
Layer 3 oz sliced roast beef onto each roll, followed by a slice of sharp cheddar cheese. Sprinkle with black pepper.
Return open-faced sandwiches to the oven for 3–4 minutes, just until the cheese begins to melt, then top with the upper half of each roll and serve warm.