Combine the coriander seeds, mustard seeds, rosemary and garlic in a food processor or mini chopper. Pulse until the herbs and spices start to form a paste. Add the olive oil and continue to pulse until the ingredients have a consistency of a thick paste. Rub this mixture over all sides of the rib roast and season generously with the salt and freshly ground black pepper. Let the roast sit on the counter at room temperature for 1 hour.

Place the onion, carrots and celery in the bottom of a heavy roasting pan. Drizzle with olive oil and season with salt and freshly ground black pepper. Place the roast, rib side down on top of the vegetables. Pour 1 cup of the stock into the pan.

Roast at 450ºF for 25 minutes. Then lower the temperature to 350ºRoast for an additional 16 minutes per pound total (in other words, for a 6-pound roast, the total cooking time should be 96 minutes, so roast for an additional 71 minutes after the initial 25 minutes). Baste the roast with the juices from the pan every 20 minutes. If the liquid starts to dry out, add some additional stock.

Check the temperature by inserting an instant read thermometer into the center of the roast. It should reach 125ºF for medium-rare and 130ºF for medium.

Remove the roast from the roasting pan and transfer it to a cutting board. Tent the roast with foil and let the roast rest for at least 25 minutes before slicing.

Remove the vegetables with a slotted spoon. Pour the juice from the pan into a measuring cup or fat separator. Discard any fat that rises to the top.

Serve a thick slice of the roast with the vegetables and jus from the pan.