Classic Roast Prime Rib Au Jus Recipe

Ingredients (6)

• 1 standing beef rib roast, 4 to 7 ribs, 9 to 18 pounds
• 2 to 3 tablespoons unsalted butter, softened
• 2 to 3 teaspoons kosher salt (or other larger grain, flake-style salt)
• Fresh coarsely ground black pepper, to taste
• 2 tablespoons all-purpose flour
• 1 quart (4 cups) beef broth, cold