braised lamb shanks

Ingredients

4 - 6 lamb shanks (or 2 big ones), trimmed of excess fat
1 large onion, diced
6 cloves garlic, minced [optional]
2 large carrots, sliced 1/2-inch thick
1/4 cup flour
4 cups beef stock
1 1/2 cups red wine (Merlot, Pinot Noir, Chianti, etc.) [optional - substitute with extra stock].
14 oz tomato puree
2 tablespoons tomato paste
2 beef bouillon cubes, crushed
1 teaspoon fresh rosemary, finely chopped
2 tablespoons fresh parsley, finely chopped ,divided
2 bay leaves
Salt and pepper to taste

Wash and pat dry lamb shanks with paper towel.
Heat 1 tablespoon oil in a dutch oven over medium-high heat. Sear two shanks in the hot oil until browned on all sides. Repeat with remaining shanks and oil. Transfer to a plate, tent with foil to keep warm, set aside.
In the pan juices, sauté the carrots and diced onions until softened, (about 3 minutes), then add garlic and cook for 1 minute.
Add flour and cook for 2 – 3 minutes.
Add stock, wine, puree, tomato paste, bullion and herbs. Stir to combine.
Return the shanks to the pot.
Cover and bring to a boil, then reduce heat to low and simmer for 1 1/2 – 2 hours, stirring occasionally, until the meat is falling apart.
Garnish with parsley and serve with mashed potatoes or rice.

To quickly thicken the sauce once the shanks are cooked through and tender:

Make a slurry of 3 tablespoons cornstarch with 1/4 cup of the sauce from the pot.
Pour the mixture into the simmering sauce, stirring quickly until completely blended.
Let simmer for 4-5 minutes, or until thickened to desired consistency.

I don't know how they are cooking 4-6 lamb shanks at a time? (maybe they are smaller than the 2 big ones I had)