Lightly dust your ossobuchi with flour and sauté them in vegetable oil in a sauté pan or braiser large enough to hold them all in one layer. Turn the pieces from time to time until they are nice and golden brown on all sides. Remove them and set aside.
Add a nob of butter to the pan, then add the minced onion, carrot and celery. Let the minced veg sauté gently until soft.
Now return the ossobuchi to the pan and give them a turn in the aromatic vegetables. Let everything sauté gently together for a few minutes, turning the ossobuchi from time to time and seasoning with salt and pepper as you go.
Pour in a good glug of white wine to the skillet and let simmer, continuing to turn the turkey pieces from time to time, until the wine has evaporated.
Add the broth and tomato to the pan, along with the bay leaf, and bring to a gentle simmer. Cover and let braise for a good 45-60 minutes, or until the turkey is tender.
While the turkey is braising, make your gremolata by mincing together the parley, garlic and lemon zest into a fine paste.
When your ossobuchi are done, add half the gremolata to the skillet, together with a ladleful of water or broth if the sauce has reduced too much. Let simmer uncovered until you have a nice sauce, which should be abundant but thick and very flavorful. Taste and adjust for seasoning.
Serve your ossobuchi napped with the sauce and sprinkled with the remaining gremolata.