Preparing the Leg of Lamb:

1. Preheat Your Oven: Preheat your oven to 325°F (160°C). This lower temperature is ideal for slow roasting, ensuring tender and juicy lamb.
2. Prepare the Garlic: Peel and mince the garlic cloves finely. You can use a garlic press or mince them by hand. The finer the mince, the more the garlic flavor will infuse into the lamb.
3. Season the Lamb: Pat the leg of lamb dry with paper towels. This helps to get a good sear. Generously rub the entire leg of lamb with sea salt and freshly ground black pepper. Be sure to season all sides, including the underside. Don’t be afraid to be generous with the seasoning, as a large cut of meat needs ample salt to bring out its flavor.
4. Create Garlic Pockets: Using a sharp paring knife, make small incisions all over the leg of lamb, about 1-2 inches deep. Insert the minced garlic into these pockets, distributing it evenly across the lamb. This ensures that the garlic flavor penetrates deep into the meat as it roasts.
5. Sear the Lamb (Optional but Recommended): Heat olive oil in a large Dutch oven or oven-safe roasting pan over medium-high heat. Searing the lamb before roasting adds a layer of flavor and helps to create a beautiful crust. Sear the leg of lamb on all sides until browned, about 2-3 minutes per side. This step is optional, but highly recommended for enhanced flavor and texture.
6. Add Aromatics and Red Wine: Place the sprigs of rosemary and thyme around the leg of lamb in the roasting pan. Pour the entire bottle of red wine into the pan, around the lamb. The red wine will create a braising liquid as the lamb roasts, keeping it moist and infusing it with flavor.

Roasting the Leg of Lamb:

7. Roast in the Oven: Cover the Dutch oven or roasting pan tightly with a lid or aluminum foil. Place it in the preheated oven and roast for approximately 3-4 hours, or until the lamb is fork-tender. The cooking time will depend on the size of your leg of lamb and whether it is bone-in or boneless. A bone-in leg may take slightly longer. The lamb is ready when it is easily pierced with a fork and the meat is pulling away from the bone (if bone-in).
8. Check for Doneness: To check for doneness, insert a meat thermometer into the thickest part of the lamb, avoiding the bone. For medium-rare, aim for 135-140°F (57-60°C). For medium, aim for 140-145°F (60-63°C). For medium-well, aim for 145-150°F (63-66°C). Lamb is often best enjoyed medium-rare to medium, as it can become dry if overcooked.
9. Rest the Lamb: Once the lamb is cooked to your desired doneness, remove it from the oven and carefully remove it from the roasting pan. Place the lamb on a cutting board and tent it loosely with aluminum foil. Let the lamb rest for at least 15-20 minutes before carving. Resting allows the juices to redistribute throughout the meat, resulting in a more tender and flavorful roast.

Making the Butter-Braised Spring Onions:

10. Prepare the Spring Onions: While the lamb is resting, prepare the spring onions. Trim the roots from the spring onions and remove any wilted or damaged outer layers. Cut the spring onions into roughly 2-inch lengths, keeping the white and green parts separate for now if you prefer a more delicate braise for the greens (though you can braise them all together).
11. Braise the Spring Onions: In a large skillet or pan, melt the butter over medium heat. Add the white parts of the spring onions (and the green parts if braising together) and cook for 2-3 minutes, until slightly softened.
12. Add Broth and Simmer: Pour in the chicken broth (or vegetable broth) and bring to a simmer. Reduce the heat to low, cover the pan, and braise the spring onions for 10-15 minutes, or until they are tender-crisp and have absorbed some of the broth. If you separated the green parts, add them in the last 5 minutes of braising to keep them bright green.
13. Season and Serve: Season the braised spring onions with salt and pepper to taste.

Carving and Serving:

14. Carve the Lamb: After the lamb has rested, carve it against the grain into slices. If you have a bone-in leg, carve around the bone first to remove the meat.
15. Serve and Enjoy: Arrange the sliced leg of lamb on a platter and spoon the braised spring onions and the red wine braising juices from the roasting pan over the lamb. Serve immediately and enjoy your delicious Ostara feast!