Dredge lamb shanks in flour; brown on all sides in hot oil in a large skillet. Place lamb in a large roasting pan; add ale and next 5 ingredients.
Bake, covered, at 375° for 2 hours. Uncover and bake 1 more hour. Skim fat from drippings.
Serve lamb shanks and drippings with mashed potatoes. Garnish, if desired.
Note: For testing purposes only, we used Guinness Stout.