Lightly coat the prime rib in olive oiland generously season with salt and freshly ground black pepper.
Pour a splash of olive oil in a hot pan and lightly brown all sides of the roast, including the ends, to seal the meat and lock in the juices.
Spread the sliced onion and garlic across the surface of an oven safe dish and place the roast on top of the onions. Scatter sage leaves over the prime rib roast and tuck them under the roast’s twine.
Pour the beef stock over the onions, cover the dish well with tinfoil and roast the prime rib for 25 minutes at this temperature, basting occasionally with the braising juices.
Reduce the heat to 180°C/350°F and continue to roast for another 1 hour 15 minutes before removing the tinfoil and allowing the meat and sage leaves to crisp up for a further 30 minutes. If using a meat thermometer, the temperature should read approximately 50°C/125°F for medium-rare.
Remove the prime rib from the oven and transfer to a chopping board. Loosely cover with tinfoil and allow it to rest for 15 to 20 minutes.
Make the gorgonzola sauce whilst the roast is resting. Melt thebutter in a saucepan over a mediumheat and cook the garlic until caramelised.
Pour in the cream and stir in the gorgonzola cheese until melted and the sauce is smooth. Remove from heat, add the pink peppercorns and season to taste with salt. Serve whilst warm.
Carve the roast into thick slices around each bone and serve with the creamy gorgonzola and pink peppercorn sauce and roasted root vegetables of your choice.