Pat the meat dry with paper towels to remove any excess moisture. the meat will brown better when they are dry. Season each shank with salt and freshly ground black pepper.
In a large Dutch oven pot or a deep oven safe pan with lid , heat vegetable oil until smoking on the stove. Add Osso Bucco to the hot pan and brown all sides, about 3 minutes per side. Remove browned shanks and set aside.
On a medium heat, in the same pot, add the onion, garlic and balsamic vinegar, season with salt and pepper at this point to help draw out the moisture from the vegetables. Saute until soft and translucent, about 8 minutes. Add the salsa and mix well. Return browned shanks to the pan. Add the rosemary and thyme and 2 cups of the bison stock and bring to a boil. Reduce heat to low, cover pan and place in oven at 300 degrees F. for about 2-3 hours or until the meat is falling off the bone. Check every 15 minutes, turning Osso Bucco and adding more stock as necessary. The level of cooking liquid should always be about 3/4 the way up the shank.
Carefully remove the cooked Osso Bucco from the pot and place in decorative serving platter.
Pour all the juices and sauce from the pot over the shanks. Garnish with chopped parsley and lemon zest.