In a large pot or Dutch oven, cook the bacon over medium heat until most of
the fat has rendered and the bacon starts to crisp. Remove bacon with a slotted
spoon, set aside, reserve pan and bacon fat.
Salt and pepper the beef shanks liberally.
Add flour to a bowl. One at a time dredge shanks in the flour until well coated.
Return the Dutch oven to heat, allow the bacon fat to get hot but not smoking.
Sear the shanks in bacon fat until browned on both sides. Remove shanks from pot.
Add olive oil to pot along with carrots, celery and onion. Cook until softened,
about 8 minutes.
Add the beer, scraping to deglaze the bottom. Stir in the tomato paste.
Return shanks and bacon to the pot. Pour in broth until shanks are ¾ of the way
covered.
Allow liquid to simmer but not boil for 3 to 3 ½ hours or until meat is tender
and falling off the bone. While shanks are cooking, turn over every 30 to 45 minutes. Add additional broth to maintain a liquid level that is about ¾ of the way up the side of the shanks.
Combine all gremolata ingredients in a small bowl.
Serve with pan sauce, topped with gremolata, over polenta, rice or mashed potatoes.