Take shanks out of the refrigerator and let sit at room temperature for 45 minutes.
Season them all over with salt and pepper.
Meanwhile, heat the oil in the stock pot over medium heat until shimmering, and add shanks one at a time, turning using tongs so that they brown on all sides. Make sure you also brown the top and bottom of the shanks; you may have to hold each shank to brown it on the ends. Remove each to a bowl when browned and drain the pot of all except 2 tablespoons of excess fat.
Return shanks to the pot and add stock and wine. The only rule is you must cover the shanks with the liquid, so equal amounts of both, or stock only, to cover.
Raise the heat to high and bring the liquid to a boil, then lower to a simmer. Cover the pot and cook shanks for 2 ½ hours over low heat. Using a fork, check to see if the shanks are tender; the easily penetrate the flesh. When tender, add any diced vegetables and zest you’ve prepared, if any, cover the pot and cook another 30-45 minutes. The shanks are done when they are falling off the bone easily with a light twist of your fork.