I just love lamb, and this is an easy Dutch oven braise for them. I like to cook them til they are practically falling off the bone, thicken the sauce with a slurry of water, flour and cornstarch, and then serve them over a rice pilaf with a Greek or fattoush salad.
Preheat the oven to 350°F. with rack on low middle position. Roll the lamb shanks in the seasoned flour and set aside. In a large Dutch oven, melt the butter and olive oil together until hot but not smoking. Add the shanks and brown on all sides to golden brown. Remove shanks to a plate.
In the oil that is left, lightly brown the onion, celery and garlic, being careful not to burn the garlic. When veggies are tender, add the tomato paste and saute it for a minute or two while stirring. Then pour in the chicken stock and wine (or sherry) and replace the shanks into the Dutch oven. Cover and place in oven for 1 hr.
Mix the chopped herbs and lemon zest together in a small bowl. (Keep juice for later)
After the hour braise, open the lid and add 1/2 of the chopped herbs and lemon zest. Replace cover and continue to bake until lamb shanks are tender.(Check occasionally to make sure the liquid has not evaporated. If so, add more stock or wine) When you remove the Dutch oven from the oven, Remove the shanks to a plate and keep warm. Add the remaining herbs mixture, and a squeeze (about 2-3 tsp) of lemon juice.
To thicken the sauce, mix cool water, cornstarch and flour in a small jar fitted with a tight lid. Shake vigorously until well mixed, then whisk into the hot liquid and cook over medium heat, whisking frequently, until thickened. Taste and adjust seasonings.
Serve the lamb shanks over a rice pilaf and top with the sauce. For garnish, a little lemon zest and chopped fresh parsley would be nice. Also, you might like to serve a lemon wedge on the side for those people who like a little more lemony flavor.
There is a "condiment" called Gremolata that is simply grated zest of a lemon, 1/4 c. finely chopped parsley and 1 to 3 finely minced garlic cloves. (Some cooks add a touch of EVOO and a little salt to this mix) You may use this as a garnish if desired or pass it for guests to use.