Pour off all but 2 tablespoons of the fat from the casserole. Add the onion, carrot, celery and a generous pinch each of salt and black pepper and cook over moderately high heat, stirring occasionally, until the vegetables are softened and just starting to brown, about 10 minutes. Stir in the garlic, anchovies, lemon zest and crushed red pepper and cook until fragrant. Add the wine and simmer until reduced by half, about 3 minutes. Add the tomatoes, stock, thyme, rosemary and bay leaves and bring to a boil. Pour the mixture over the shanks in the roasting pan. Cover tightly with foil and braise in the oven for about 3 hours, until the meat is very tender.