• Preheat oven to 170°C or 335°F (standard) or 150°C (fan).
• Place garlic, onion and rosemary in a metal roasting pan.
• Season the lamb: Place the lamb leg right side up in the pan. Sprinkle generously with salt and pepper and rub it in.
• Turn the lamb over and place it so it mostly sits on the garlic and onion. Sprinkle with more salt and pepper, rub it in.
• Add liquids and cover: Drizzle lamb with olive oil. Pour broth and water around the lamb – it won't cover it, that's ok, the lamb sinks into it. Cover with foil (don't use a lid, you want a bit of liquid to steam out).
• Slow roast: Place in the oven and roast for 4.5 hours. (See Notes for roasting time table.)
• Check the meat: Remove from the oven, remove foil. Turn lamb over. Check it to ensure the meat is tender enough to pry a bit off easily with a fork. If not, return, covered, to oven.
• Brown the lamb: Return the uncovered lamb to the oven for a further 45 minutes or until well browned.
• Rest: Remove the lamb, spoon over pan juices generously. Transfer to a serving platter, cover loosely with foil while you make the gravy (stays warm for 1 to 1.5 hours).

Gravy:

• Skim the fat: Use a large spoon to skim off and discard some of the fat from the surface of the liquid.
• Add flour: Place pan on the stove on medium high. When the liquid bubbles, add flour. Use a whisk to mix it in – this may take a few minutes as the liquid reduces.
• Add water: Once it looks like sludge, whisk in ½ to 1 cup of water until it becomes a gravy consistency to your taste. Adjust salt and pepper to taste. I I rarely add extra salt.
• Strain the gravy into a bowl, pressing juices out of the onion etc. Pour the gravy into a jug.

Serving:

• The meat is tender so you will only need tongs to tear the meat off.
• Serve with gravy!