• Preheat oven to 170C/335F (standard) or 150C/300F (fan/convection).
• Place garlic, onion and rosemary in a metal roasting pan.
• Place lamb leg right side up in the pan. (Note 2)
• 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. (Video helpful here)
• 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).
• Place in the oven and roast for 4.5 hours. (See Notes for roasting time table)
• Remove from the oven, remove foil. Turn lamb over. Check it to ensure the meat is tender (pry a bit off with a fork). If not, return, covered, to the oven.
• Return uncovered lamb to oven for a further 45 minutes or until well browned.
• Remove lamb, spoon over pan juices generously. Transfer to a serving platter, cover loosely with foil while you make the gravy (stays warm for 1 – 1.5 hours).

GRAVY:

• Use a large spoon to skim off some of the fat from the surface of the liquid.
• 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.
• Once it looks like sludge (see video), whisk in 1/2 – 1 cup of water until it becomes a gravy consistency to your taste. Adjust salt and pepper to taste – I rarely add extra salt.
• Strain gravy into a bowl, pressing juices out of the onion, etc.
• Pour gravy into a jug.