How to Make It
Put the lamb bones and scraps in a large, heavy bottomed saucepan over moderate heat. Add the chopped mushrooms and onion along with sachet and cook for 1 minute. Stir in the veal stock and the wine and bring to a boil. Lower the heat and simmer for 1 1/2 hours, or until liquid is reduced to 2 cups. Add balsamic vinegar and simmer for about 2 minutes. Remove from heat and strain through a fine sieve into a medium saucepan; discard the solids. Season to taste with salt and pepper and set aside.
Heat 2 tablespoons of the oil in a medium sauté pan over moderate heat. Add the pearl onions and sauté, shaking the pan often to lift the onions up, for 5 minutes, or until the onions are golden on all sides. Sift the sugar and the cumin over the onions, shaking the pan. Add 1/2 cup of water and cook, shaking the pan often, for about 5 minutes, or until the onions are cooked through and well-glazed. Season to taste with salt and pepper. Remove from heat and keep warm.
In a food processor, fitted with the metal blade, combine the fresh and dried shiitakes and process until finely minced. Scrape the mushrooms into a shallow container.
Line a baking sheet with a kitchen towel and set aside. Season the lamb chops with salt and pepper. Press each side of the chops into the minced mushrooms until they form a crust around the meat. Heat 2 tablespoons of oil in a large sauté pan over moderately-high heat. Carefully lay 6 chops in the pan and sear for 6 minutes, or until a crisp crust has formed. Carefully turn and sear for 6 more minutes, or until a crust has formed and the lamb is rare. Transfer to the prepared baking sheet and cover lightly to keep warm while you cook the remaining chops as above, using oil as necessary.
Meanwhile, heat the sauce over moderate heat. To serve, crisscross 2 lamb chops in the center of each of 6 warm plates. Arrange 4 onions around the perimeter of the chops. Sprinkle with parsley and drizzle the sauce over the chops and around the edge of the plate. Serve immediately.