1. Preheat oven to 350°. Combine first 3 ingredients in a shallow dish; thoroughly dredge veal shanks in flour mixture, shaking off excess. Heat drippings and butter in large Dutch oven 2 minutes over high heat, add 3 veal shanks, and brown each side 3 to 4 minutes; remove to baking sheet. Brown remaining veal shanks, and remove to baking sheet. Sauté onion and next 7 ingredients in drippings 5 minutes. Add broth and wine, deglaze by stirring to loosen particles from bottom of pan, and bring to a boil.
2. Return veal shanks to Dutch oven, and top with vegetables. Transfer to lower third of oven, cover, and bake 2 hours or until veal is fork-tender. Remove parsley sprigs and bay leaves, and add more salt and pepper, if desired.
3. Arrange veal on a heated baking sheet, and keep warm. Let vegetables cool slightly. Place one-fourth of vegetables and liquid in a blender, and add sour cream. Pulse 2 or 3 times, then blend 10 to 15 seconds or until smooth. Add salt, if desired.
4. Pool some vegetable puree on each of 6 heated dinner plates, and center a veal shank and vegetables on top. Serve remaining puree in a heated gravy boat.