Prime Rib Cooking Time: Nan's Sunday Roast, Perfected!

Ingredients

• 1 (4-6 pound) bone-in prime rib roast (standing rib roast)
• 2 tablespoons kosher salt
• 1 tablespoon freshly ground black pepper
• 1 tablespoon garlic powder
• 1 tablespoon onion powder
• 1 teaspoon dried thyme
• 1 teaspoon dried rosemary, crushed
• 1/2 teaspoon paprika
• 2 tablespoons olive oil
• 1 cup sour cream
• 2 tablespoons prepared horseradish, or more to taste
• 1 tablespoon Dijon mustard
• 1 tablespoon chopped fresh chives
• Salt and pepper to taste