Baltimore Pit Beef Sandwich with Horseradish Sauce - Martin's Famous Potato Rolls and Bread

Ingredients

• 1 Pack Martin’s Big Marty’s Rolls
• 2 Tablespoons Kosher Salt
• 1 Tablespoon Coarsely Ground Black Pepper
• 1 Teaspoon Dried Oregano
• 1 Teaspoon Garlic Powder
• 1 Teaspoon Onion Powder
• 1 Teaspoon Paprika
• 1 Teaspoon Chili Powder
• 1 4-lb Bottom Round Roast
• 1 Sweet White Onion, thinly sliced
• Horseradish Sauce
• – 1 Cup Mayonnaise
• – 1/4 Cup Prepared White Horseradish
• – 2 Teaspoons Fresh Lemon Juice
• – 2 Teaspoons Finely Minced Fresh Garlic
• – Kosher Salt, to taste
• – Freshly Ground Black Pepper, to taste