Grilled Prime Rib
The technique known as grill roasting transforms your backyard grill into an outdoor oven, achieving the same results as with oven roasting but without heating up the kitchen—ideal for warm summer days. For best results, season the roast the night before. Horseradish cream makes a delicious accompaniment: combine one part prepared horseradish with two to three parts sour cream, then season to taste with salt, pepper and fresh lemon juice.
- 1 prime rib roast, about 5 1/2 lb.
- Maldon sea salt and freshly ground pepper, to taste
- 2 Tbs. olive oil
- 2 large red onions, each cut into 6 wedges
- 2 large fresh thyme sprigs
Tie butcher’s twine around the roast in between each bone. Place the roast on a baking sheet and generously season on all sides with salt and pepper. Cover with plastic wrap and refrigerate for 12 to 24 hours.
Brush the roast with 1 Tbs. of the olive oil. Let stand at room temperature for 1 hour. In a bowl, stir together the onions and the remaining 1 Tbs. olive oil, and season with salt and pepper.
Prepare a hot fire in a grill. Place a steel grill roaster in the center of the grill, cover the grill and preheat for 5 minutes.
Place the roast, fat side down, in the pan and sear until browned, 2 to 3 minutes. Turn the roast over, bone side down. Turn off the center burners and reduce the outside burners to medium-low, adjusting them as needed to maintain the internal grill temperature at 350°F. Cover the grill and cook the roast for 45 minutes. Place the onions along the sides of the pan and lay the thyme sprigs on top. Re-cover the grill and continue cooking until an instant-read thermometer inserted into the center of the roast, away from the bone, registers 120°F for medium-rare, 30 to 60 minutes more, or until done to your liking.
Transfer the roast to a carving board, cover loosely with aluminum foil and let rest for 15 minutes. Carve the roast and serve the onions alongside. Serves 4 or 5.