Season the veal shanks with salt and pepper and dredge them in the flour, shaking off the excess.
In a heavy pot large enough to hold the veal shanks in one layer, heat 3 tablespoons of the butter and 3 tablespoons of the oil over moderately high heat until the foam subsides, and brown the shanks, adding some of the additional butter and oil as necessary.
Remove shanks to a platter.
Add a little of the wine to the pot to deglaze, scraping up the brown bits clinging to the bottom and sides of the pot. Add the rest of the wine and boil until the liquid is reduced to about 1/2 cup.
Reserve the wine reduction in a bowl.
Add the onion, carrots, celery, and garlic in the remaining butter over moderately low heat, stirring occasionally, until the vegetables are softened.
Add the shanks with any juices that have accumulated on the platter, the reserved wine mixture, and enough of the broth to almost cover the shanks.
Spread the tomato paste over the shanks, add the thyme, parsley, bay leaf, and more salt and pepper to taste.
Bring the liquid to a low boil, then reduce to a lively simmer. Braise the shanks, turning every half hour until very tender, about 2 hours.
Remove the shanks to a platter, take off the strings and cover with foil to keep warm.
Skim the fat from the pot, then strain the pan juices into a saucepan, pressing hard on the solids. **(see note below)
Boil the juices until they are reduced and sauce begins to thicken. Add salt and more pepper to taste. Return shanks to pot to heat through.
Serve over a simple risotto, garnish with more chopped parsley, and don't forget to provide some cocktail forks to get at the marrow.
Heaven!!
>Notes:
**I don't do the straining the vegetables step. I cut my veggies super fine, and leave them in the sauce. I have also tried pureeing the sauce so it is smooth, but I like the itty bitty chunks of veggies in there. The last time I made it, I used my food processor to do the veggies - a real "aha!" moment. Cut so much time off of prep, and the veggies were super finely chopped, adding texture to the sauce but not too much.
Using red wine in this dish is not the norm – every recipe I've seen calls for white wine. I like the flavor of red much better, plus I get to drink the rest ;)
Fresh or canned tomatoes are typically used, but I like the richness of the tomato paste.
If you like it a little "beefier" tasting, use all beef broth instead of the chicken/beef mix.
Osso Bucco is traditionally served with gremolata on top, but I don't care for it. Here is the recipe in case you like it:
Gremolata
1/2 cup minced fresh parsley leaves (preferably flat-leafed)
2 tablespoons freshly grated lemon zest
1 tablespoon minced garlic
Sprinkle over cooked shanks.