Lower the heat to medium and add the carrot, celery and onion. Season with a pinch of salt and cook, stirring occasionally, until the vegetables have slightly softened, around 5 minutes. Add the garlic and cook, stirring, until fragrant, 60 seconds. Add the tomato paste and cook, stirring to incorporate, 2 minutes. Add the wine, if using, and cook, stirring, until reduced in volume by half. Add the crushed tomatoes, beef broth, rosemary, thyme, bay leaves and black pepper, raise the heat to medium-high, and cook, until the liquid reaches a simmer. Nestle the browned lamb shanks in the sauce. If necessary, add more broth until the meat is almost fully submerged. Cover the pot with a lid and transfer it to the oven. Cook until the meat is very tender and falling off the bone, around 2.5 hours. If the meat is still not tender after 2.5 hours, continue cooking and checking on it every 30 minutes.