Trim the skin/fat layer from around the pork shank with a very sharp knife. Tie the shank with kitchen twine to hold it together during cooking.
Dredge pork shanks in the flour till evenly coated and season all over with salt and pepper.
Sear shanks over medium high heat about 2 minutes per side. Remove shanks to a platter and set aside.
If the oil is burnt, wipe the dutch oven with a paper towel but leave the brown bits on the bottom. If it looks too dry add a tablespoon of butter or oil and melt before adding the onions, carrots and celery to the dutch oven.
Cook over medium heat about 5 minutes. Add the garlic and cook 1 minute more. Then add the red wine, reduce the heat and scrape up all the brown bits from the bottom of the Dutch oven.
Add the stock, tomatoes, tomato paste and red pepper flakes and herbs to the pan. Return the shanks to the pot and simmer about 5 minutes.
Preheat oven to 325° F while sauce is simmering.
Cover and allow shanks to braise 3 hours in the oven.
If there is fat floating on top of the sauce skim some off but leave some because it holds incredile flavour. (I didn't have much because the skin/fat layer has been removed.) Stir sauce well.
Transfer shanks to a platter and spoon sauce over it generously. Garnish with parsely if desired.
Serve over pasta, polenta or potatoes.
Notes
Note: You may have sauce left over. It is delicious over pasta on its own or thin it down to make broth for a soup.