Prime Rib Roast with Red Wine Au Jus

Bahan-bahan (8 porsi)

• 6 to 7 pounds prime rib roast, (bone in)
• salt and pepper, (to taste)
• 1 teaspoon garlic salt
• 1 teaspoon onion salt
• ½ cup (1 stick) unsalted butter
• ½ medium onion, (diced)
• 2 medium garlic cloves, (minced)
• 4 cups beef stock
• 2 cups red wine