Preheat oven to 170°C/335°F (standard) or 150°C (fan).

Place garlic, onion and rosemary in a metal roasting pan.

Season lamb: Place lamb leg right side up in the pan. Sprinkle generously with salt and pepper and rub it in.

Turn 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.

Slow roast: Place in the oven and roast for 4.5 hours.

Check 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 lamb: Return uncovered lamb to oven for a further 45 minutes or until well browned.

Rest: Remove lamb, spoon over pan juices generously. Transfer to serving platter, cover loosely with foil while you make the gravy.

Skim 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.

Add water: Whisk in ½ - 1 cup of water until it becomes a gravy consistency to your taste. Adjust salt and pepper to taste.

Strain gravy into a bowl, pressing juices out of the onion etc. Pour gravy into jug.

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