For this dish, gather the following ingredients:

• 2.25kg/5lb whole shoulder of lamb, with skin on
• 4 garlic cloves, sliced
• 2 large onions, cut into quarters
• 750g/1lb 10oz waxy potatoes, such as Desiree, peeled and cut into thick 2cm/¾in slices
• 570ml/1pint hot lamb or beef stock
• Green vegetables, to serve

For the gravy:

• 3 tbsp lamb fat (see method)
• 50g/1¾oz plain flour
• 450ml/16fl oz hot lamb or beef stock
• 100ml/3½fl oz red wine
• 1–2 tsp redcurrant jelly
• A few drops of Worcestershire sauce
• Gravy browning (optional)

Now, let's get cooking!

1. Preheat your oven to 220C/200C Fan/Gas 7.

2. Begin by placing the lamb, skin-side up, on a board. Using a sharp knife, make irregular holes through the skin and insert the sliced garlic into these openings.

3. Transfer the lamb to a roasting tin and let it roast for approximately 20 minutes until the skin turns a tempting shade of brown. Carefully turn the lamb over and continue roasting for another 20–30 minutes until it achieves a lovely even browning.

4. While the lamb is roasting, boil the onions in water for 10 minutes. Then, add the potatoes to the boiling water and let them cook for an additional 4 minutes. Drain them well.

5. Remove the lamb from the roasting tin and add the onions and potatoes, mixing them together. Pour the hot stock into the tin and place the lamb on top. Cover the tin securely with foil.

6. Reduce the oven temperature to 160C/140C Fan/Gas 3 and cook the lamb for 3½–4 hours until it reaches a delectable tenderness. Once done, transfer the lamb to a board. You can strain off the fat from the tin into a small bowl for later use in the gravy. Increase the oven temperature again to 220C/200C Fan/Gas 7 and return the potatoes and onions to the oven to brown for approximately 25 minutes.

7. Now, let's whip up the savory gravy! Spoon the lamb fat into a saucepan and add the plain flour. Stir over heat for about 30 seconds. Gradually whisk in the hot stock, red wine, redcurrant jelly, Worcestershire sauce, and gravy browning if using. Keep whisking until the gravy thickens and starts to bubble.

8. Carve the tender lamb and serve it with the flavorful gravy, alongside the roasted potatoes and onions. Add some green vegetables on the side to complete this scrumptious meal.

Enjoy this mouthwatering feast with your loved ones and savor the delicious flavors that only a well-prepared shoulder of lamb can provide!