01 - Preheat the oven to 325°F.
02 - Pat the veal shanks dry with paper towels. Mix the flour, salt, and pepper in a shallow dish. Lightly dredge each shank in the flour mixture, shaking off excess.
03 - In a large Dutch oven, heat olive oil and butter over medium-high heat. Brown the veal shanks on all sides for about 3–4 minutes per side. Remove and set aside.
04 - Add onion, carrots, and celery to the pot and sauté until softened, about 8 minutes. Add garlic and cook for 1 minute.
05 - Pour in the white wine, scraping up any browned bits from the bottom. Simmer for 2–3 minutes until slightly reduced.
06 - Add the tomatoes with juices, chicken stock, thyme, bay leaves, and lemon zest to the pot. Stir to combine.
07 - Return the veal shanks to the pot, nestling them into the sauce. Bring to a simmer.
08 - Cover the pot and transfer to the oven. Braise for 2–2.5 hours, until the meat is fork-tender and nearly falling off the bone.
09 - Remove bay leaves and skim off any excess fat from the surface. Optionally mix gremolata ingredients and sprinkle over the osso buco before serving. Garnish with fresh parsley.