In a large skillet, heat olive oil over medium-high heat.
Season shanks with salt and pepper and dredge in the flour, shaking off the excess. Add shanks to skillet. Cook until deep golden brown on both sides. Only turn once, about 12 minutes per side. Transfer shanks to a bowl.
Reduce heat to medium-low. Add onion and garlic and more oil if pan looks too dry. Sauté onions and garlic until tender, about 4 - 6 minutes.
Deglaze the onions with the wine, scrape the bottom of the pan and reduce liquid by half. Return shanks and any liquid in bowl to skillet. Add tomatoes, broth and rosemary to skillet. Cover partially and simmer until veal is very tender and begins to fall off bones, about 2 hours.
Meanwhile, combine all the Gremolata ingredients in small bowl.
Serve shanks with sauce and garnish with Gremolata.