– 4 lamb shank – Salt and black pepper, to taste – 2 tablespoons olive oil – 2 onions, chopped – 4 cloves garlic, minced – 2 carrots, chopped – 2 celery stalks, chopped – 2 sprigs of rosemary – 2 sprigs of thyme – 2 bay leave – 1 bottle (12 oz) stout beer – 1 cup beef or lamb broth – 2 tablespoons tomato paste – 2 tablespoons all-purpose flour – Mashed potatoes or creamy polenta for serving – Chopped fresh parsley for garnish