Preheat oven to 350f and set the rack to the middle level leaving enough room to accommodate a Dutch oven.

Season the lamb shanks well on all sides with salt and pepper then dredge in the flour and shake off any excess.

Heat a large Dutch oven to medium heat with olive oil and sear the shanks until brown on all sides (approximately 10 minutes total). Place all the seared shanks in a plate off to the side.

Pour off the excess fat from the pot, leaving only 3 tablespoons worth. Add the onion, carrot, and celery to the pot along with a pinch of salt. Saute the vegtables until soft (about 10 minutes).

Add the garlic and cook until fragrant then add the tomato paste. Cook for 5 minutes, stirring frequently. If the paste starts to burn add a few ounces of water and/or lower the heat a touch.

Add the wine to the pot and turn the heat to high. With a wooden spoon, scrape all of the brown bits from the bottom of the pot. Boil for 2 minutes then turn the heat off.

Add the lamb shanks, beef stock, bay leaves, rosemary sprigs, and black pepper to the pot. Mix well then cover with a heavy lid. Place the pot into the oven and cook for 2 hours then remove the lid and cook for another 30 minutes or until the top of the lamb has browned a bit.

Remove the lamb shanks from the pot and degrease the sauce by skimming some of the fat off with a spoon. Taste test, and if needed, season with more salt and pepper.

Remove the rosemary and bay leaves and blend the sauce with an immersion blender to thicken. Alternatively, boiling for 5-10 minutes or using a cornstarch slurry works as well. Serve the lamb shanks with crusty bread or over mashed potatoes, polenta, or rice.