Step 1

Preheat oven to 350 degrees F (175 degrees C).

Step 2

With a small sharp knife, make cuts in the meaty side of the beef roast, and insert slivers of garlic into the cuts. Lay the roast in a roasting pan with the rib side down. Mash the 3 cloves of minced garlic, horseradish, thyme, rosemary, kosher salt, black pepper, and olive oil in a bowl to make a paste. Rub the paste all over the roast, including the rib bones. Scatter the carrots, celery, and onion into the roasting pan around the meat.

Step 3

Roast the meat in the preheated oven until browned and a quick-read meat thermometer inserted into the thickest part of the roast reads 135 degrees F (57 degrees C), for medium-rare meat, about 2 hours and 20 minutes.

Step 4

Remove the roast to a carving board, and allow to rest for 10 minutes. The temperature of the roast should rise to 145 degrees F (65 degrees C).

Step 5

Pour the pan drippings into a bowl, and skim excess fat. To serve, carve the roast into 1-inch thick slices, arrange slices on a platter, and place vegetables around the meat. Pour the pan juices over the meat and vegetables.