Preheat oven to 160°C.

Heat olive oil in a large ovenproof casserole dish on the stove.

Season lamb shanks with salt and pepper.

Brown 3 lamb shanks in the casserole dish over moderate heat (about 8 minutes).

Set the browned shanks aside.

Add the remaining 3 shanks and rosemary to the casserole dish and brown.

Add minced garlic and cook for 1 minute.

Remove from heat and return the first 3 shanks to the casserole dish.

Remove lemon pulp from the preserved lemon and cut the rind into 8 pieces.

Add the lemon rind pieces, verjuice, chicken stock, garlic cloves, bay leaves, cracked peppercorns, and salt to the lamb.

Bring the mixture to a boil.

Cover tightly and braise in the oven for 3 hours, turning the shanks occasionally, until tender.

Transfer the lamb to a platter and cover to keep warm.

Discard the rosemary stems and bay leaves.

Skim fat from the sauce in the casserole dish.

Return the shanks to the sauce and warm over moderate heat.

Spoon into bowls and serve.

Serve with mashed potato and steamed vegetables.