In a large shallow platter, season flour with salt and pepper. Dredge the veal shanks in the mixture and tap off any excess. In a large heavy skillet or Dutch oven, over medium flame, heat the oil and butter. Sear the shanks on all sides, turn bones on sides to hold in marrow. Add more oil and butter if needed. Remove the browned veal shanks and set aside.
Add onion, celery, carrots, garlic, bay leaves and parsley to the pan and cook until softened. Season with salt and pepper. Raise the heat to high, add the wine and deglaze the pan. Return the shanks to the pan, add the stock and tomatoes, drizzle with olive oil. Reduce the heat to low, cover and cook for about 1 1/2 hours or until the meat is tender. Baste the meat a few times during cooking. Remove the cover, continue to simmer for 10 minutes to reduce the sauce a bit.
For gremolata: combine all ingredients together in a small bowl. Strew the gremolata over the osso buco before serving. Serve osso buco with Saffron Risotto.
In a saucepan, bring chicken broth to a simmer. Keep warm over low heat.
In a large saute pan, melt butter over medium heat. Add oil and rice and cook for 2 minutes, stirring to coat each grain. When rice begins to make a crackling sound, add saffron threads. Add 1 cup of the warm chicken broth and cook, stirring, until the rice has absorbed the liquid. Add the remaining broth, 1 cup at a time. Continue to stir, allowing the rice to absorb each addition of broth before adding more. Test the rice for doneness, it should be al dente but creamy. Remove risotto from heat, add grated cheese, salt and pepper. Serve at once with Osso Buco Milanese.