1. Preheat oven to 375 degrees Fahrenheit.
2. Rub the rib roast with salt and pepper, shallots, grainy mustard, olive oil, garlic and rosemary. Set aside.
3. Add the onions, carrot and celery in the bottom of a pan.
4. In a skillet on high heat, caramelize all sides of the rib roast.
5. Add the roast over the vegetables in the pot and add beef stock.
6. Pop into the oven for an hour and a half. If the meat is too rare for your taste, leave in the oven for an additional 30 minutes.
7. Slice, plate along with the vegetables and serve with some horseradish.