Preheat oven to 350° F. Season lamb shanks with salt.
Heat the oil in a Dutch oven or an oven-proof, thick-bottomed, pot with a tight fitting cover on medium high heat on the stovetop. Working in batches if necessary, brown the lamb shanks in the pot on all sides.
Remove shanks to a dish.
Sauté the onion, carrot, celery:
Add onion, carrot and celery and sauté for 5 minutes, stirring often.
Add potatoes and cook another 2 minutes.
Add the garlic, lamb shanks, and herbs (except for the mint). If using, add the sherry and raisins; bring the sherry to a boil and cook for 2 minutes.
Add the stock and bring to a simmer.
Remove from heat, cover the pot and bake in the oven for 1 1/2 or 2 hours or until shanks are tender.
Strip meat from bones:
Remove the shanks, strip the meat from the bones and return the meat to the pan.