Creating Lamb Shank with Rosemary Jus is a fulfilling culinary adventure. Follow these simple steps for wonderful results:

1. Preheat the Oven: Set your oven to 325°F (160°C) to prepare for slow cooking.
2. Sear the Lamb: In a large oven-safe pot or Dutch oven, heat the olive oil over medium-high heat. Season the lamb shanks with salt and pepper. Sear each shank for about 4-5 minutes until browned on all sides. Remove the lamb and set aside.
3. Sauté the Vegetables: In the same pot, add the onions, carrots, and celery. Sauté for about 5-7 minutes until softened. Add the garlic and cook for a further minute.
4. Deglaze the Pot: Pour in the red wine, stirring to loosen any browned bits from the bottom. Bring this mixture to a simmer and allow it to reduce by half.
5. Add Lamb and Stock: Return the lamb shanks to the pot. Add the beef stock, rosemary, thyme, and Dijon mustard. Ensure the shanks are mostly submerged in the liquid.
6. Cover and Bake: Cover the pot with a lid and place it in the preheated oven. Bake for 2 to 2.5 hours, or until the meat is fall-off-the-bone tender.
7. Prepare the Jus: Once cooked, remove the lamb shanks and keep warm. If desired, strain the cooking liquid and return to the stovetop to simmer. Whisk in cornstarch to thicken the jus, adjusting seasoning as needed.
8. Serve: Plate the lamb shanks and drizzle the rosemary jus over the top.

These straightforward instructions will guide you in creating an incredibly satisfying Lamb Shank with Rosemary Jus.