Preheat the oven to 325°.
Add the flour to a bowl or a plate and season it very well with salt and pepper. Dredge the veal shanks on all sides in the flour and set aside.
Next, heat the olive oil in a Dutch oven over medium-high heat and sear the veal shanks until they are golden brown on all sides, about 5 to 7 minutes per side.
Remove the veal shanks and add the onions, carrots, celery, and garlic to the pot and sauté for 3 to 4 minutes before mixing in the tomato paste.
Cook for 2 minutes, add the tomatoes and then deglaze with the wine followed up by adding in the beef stock, bay leaves, parsley, thyme, and salt. Note: Make sure the liquid is seasoned very well.
Add the veal shanks back in the pot, submerge them, place a cover of the pot and cook in the oven for 2 to 2 ½ hours or until very tender and easily removes from the bone.
Gremolata: Mix together all of the ingredients in a small bowl and set aside until serving time.
To Serve: Serve the Osso Bucco and some of the sauce over top risotto or polenta and add the gremolata to the top of the veal shanks.