Step 1 Heat the oven to 300 degrees. Season the roast generously with salt and pepper and place it upside-down in a roasting pan, so it is supported by the rib bones. Roast 30 minutes, then turn the meat over and continue cooking to an internal temperature of about 140 degrees, about 2 hours.
Step 2 While the roast is cooking, combine the wild rice, 1 1/2 teaspoons of salt and the water in a large saucepan and cook uncovered over medium-high heat until the rice is tender, about 45 minutes. Drain the rice and return to the pan. Add the shallots, cranberries, pears and rosemary, cover the pan and let stand until the roast is ready.
Step 3When the roast is ready, add the walnuts to the wild rice, season to taste with salt and pepper and stir in the red wine vinegar. Spoon as much of the rice filling as possible into the center of the crown roast, spoon some of the fat from the bottom of the roasting pan over the stuffing, and return the meat to the oven. (Place the remaining wild rice stuffing in a baking dish alongside the roast.) Cook the roast to an internal temperature of 145 degrees, an additional 10 to 15 minutes.