Ingredients

• 1 (2-rib) tied prime beef rib roast (from small end; about 4 1/2 lb trimmed)
• 1 1/2 tablespoons kosher salt
• 1 teaspoon black pepper
• 2 tablespoons all-purpose flour
• 1 1/2 tablespoons English dry mustard (preferably Colman's)
• Accompaniment: onion gravy
• an instant-read thermometer

Instructions

1. Put oven rack in lower third of oven and preheat oven to 450°F.
2. Put beef, fat side up, in a small roasting pan and sprinkle all over with salt and pepper. Stir together flour and dry mustard, then pat onto top and sides of roast to form a thick coating.
3. Roast beef 20 minutes. Reduce oven temperature to 350°F and roast until thermometer inserted into center of meat registers 115°F, about 1 1/4 hours more. Transfer beef to a cutting board and let stand, uncovered, 25 minutes. Meat will eventually reach 125°F (medium-rare).