Preparation

1. Preheat oven to 270°C (Th. 9)
   
   Prepare the perfumed butter:
   Finely chop the red bell pepper. Mix it with the garlic and parsley, then incorporate the mixture into the soft butter with a fork. Form into a roll, wrap in cling film and refrigerate.

2. Spread an even layer of Le Guérandais coarse grey Guérande salt in a roasting tin the size of the prime rib, then add the rosemary sprigs.
   

3. Heat the oil in a large frying pan over high heat, and sear the rib for 2 minutes on each side, then remove and season with pepper on both sides. Place the rib on the bed of salt (there's nothing wrong with the bone protruding from the pan). Cover the entire rib with the remaining salt to form a thick layer.

4. Place in the oven at half-height and cook for 40 to 45 minutes, depending on the desired degree of doneness (rare or medium-rare). Remove the rib from the oven and leave to rest for a good ten minutes.

5. Serving:
   Break off the salt crust and cut the prime rib into thick slices. Place a slice of herb butter on each slice and serve immediately.