Slow-Roasted Leg of Lamb

Start with the leg itself. Ask your butcher to leave the fat cap on and to give you something with a bit of bone showing at the shank — bone conducts heat differently from muscle and gives you a handle for carving later. Trimming excess fat matters less for calories than for the scoring that follows: score only the fat, never into the muscle, because a cut into the meat is a door for juices to leave through while it cooks slowly for two and a half hours. The diamond pattern isn't decoration — it opens the fat up so the rub actually gets under it instead of sliding off a slick surface, and it lets rendered fat baste the meat from above as it melts.

Garlic and rosemary pounded to a paste, not chopped, because a paste clings to scored fat and sits in the cuts; chopped bits roll off in the oven's first ten minutes of heat and end up charred and bitter in the tray rather than flavouring the meat. If you don't own a mortar, the flat of a knife blade and a cutting board does the same crushing job, just slower and with more swearing. Rosemary's job here is resinous and sharp against lamb's fat — if you can't get fresh, use it sparingly dried, a third of the amount, because dried herbs are concentrated and go bitter fast in a paste that sits raw on meat overnight.

The overnight fridge rest is the unglamorous half of this recipe and the half that actually earns its flavour. Salt pulls moisture out of the surface first, then that moisture — now carrying dissolved salt and the paste's oils — gets reabsorbed back into the meat over hours, carrying seasoning with it below the surface. Twenty minutes of rubbing can't do that; it can only coat. This is also why the dish should be uncovered loosely or under cling film rather than sealed airtight — you want some air circulation so the surface dries slightly, which helps the fat render and crisp rather than steam later in the oven.

The vegetables under the leg — carrot, onion, garlic, a rosemary sprig — aren't really there to be eaten as a side. They're a trivet and a stock-maker in one: they lift the meat fractionally off the dish so it doesn't fry in its own fat on direct metal, and as the wine and stock reduce around them over two hours, they give up their own sugars and aromatics into what becomes your gravy base. Carrot bends rather than snaps when it's given up most of its structure to the liquid — that's roughly your cue that the braising liquid has had enough time working, though by then the leg itself has long been the main concern, not the veg.

Wine and stock together do a job neither does alone. Wine's acidity helps break down a little of the surface protein and cuts the richness of the lamb fat in the final sauce; stock gives body and saves you from an all-acid, thin gravy. If you've no wine open, a decent stock alone with a splash of vinegar at the end gets you most of the way — the alcohol mostly cooks off anyway over two hours, so you're really after the acidity and flavour compounds, not a buzz.

Cornflour at the end is there for one reason only: to thicken a sauce that's otherwise thin because it's mostly rendered fat, wine and stock reduction with nothing starchy in it. Skim the fat first or the cornflour will thicken a greasy liquid into a greasy gel, which helps nobody. Mix it to a thin paste with a little cold water before adding to hot liquid — straight into the pan it clumps, because starch granules need to be separated by liquid before they hit heat, or they just seize together on contact. Any neutral starch does the same job if you're out of cornflour — potato starch, even a flour-and-butter paste whisked in, though that brings its own taste that cornflour doesn't.