Heat oven to 325 degrees. Heat canola oil in a heavy cast iron pan. Season lamb with salt and pepper on all sides. Brown lamb in oil on all sides and set aside. Pour hot oil from pan and wipe it clean. Add the olive oil and the onion, carrot, and garlic. Stir to combine and cook until soft. Add the white wine to the vegetables and cook to reduce the wine until it has evaporated. Stir in the tomato paste, add the stock and stir.
In a saucepot or Dutch oven, add the lamb shanks and the vegetable/stock mix. Bring this to a boil and add the bouquet garni. Turn off heat and cover. Place the pot in the oven and cook for approximately 3 hours, or until lamb is tender.
To serve, spoon the soft polenta into center of each plate or bowl. Top polenta with a lamb shank and sauce. Spoon the olive tapenade mixture over each lamb shank and drizzle with extra virgin olive oil.