1. Pat the beef shanks dry and season them all over with salt and black pepper. Lightly coat each piece with flour and shake off the excess.

2. Heat the olive oil in a large Dutch oven over medium-high heat. Sear the beef shanks for about 3 to 4 minutes per side until deeply browned, then transfer them to a plate.

3. Add the onion, carrots, and celery to the same pot. Cook for 5 to 6 minutes until softened, then stir in the garlic and tomato paste and cook for 1 minute.

4. Pour in the white wine and scrape up the browned bits from the bottom of the pot. Let it simmer for 2 minutes.

5. Stir in the beef broth, crushed tomatoes, thyme, and bay leaves. Return the beef shanks to the pot.

6. Cover and bake at 325°F for 2 1/2 to 3 hours, until the beef is very tender and nearly falling off the bone.

7. Remove the bay leaves. Mix the lemon zest and parsley together and sprinkle over the dish just before serving.

8. Serve hot with polenta, mashed potatoes, risotto, or buttered noodles.