How do I slow roast a shoulder of lamb or pork?

A shoulder is the wrong shape and the wrong composition for a quick roast: it is uneven, riddled with connective tissue and seams of fat, and it contains a set of bones that make carving awkward. Cook it for four times as long as you would a leg and every one of those problems turns into an advantage.

What you'll need

• Bone-in shoulder of lamb or pork, 2–2.5kg
• A deep roasting tin and heavy-duty foil
• A probe thermometer
• Garlic, rosemary or fennel seeds, and stock, wine or cider

Step by step

1. Decide which roast you are doing before you start.A shoulder can be roasted pink and sliced, like a leg, at high heat for a short time — but it is not very good at it because of the connective tissue. Slow roasting to pull-apart is what the cut is for. The two methods have nothing in common, so pick one and commit.
2. Score, season and stud.Score the fat cap in a shallow diamond pattern without cutting into the meat. Salt it hard all over — a large joint takes far more salt than looks sensible. Push slivers of garlic and sprigs of rosemary into slits in lamb, or rub crushed fennel seed and garlic into pork.
3. Sit it on aromatics with a little liquid.A bed of halved onions, carrots and garlic keeps the joint off the base and flavours the juices. Add a mugful of stock, wine or cider — enough to steam, not enough to poach. It will also stop the tin drying out and burning over five hours.
4. Cover tightly and cook at 150–160°C.Seal the tin with foil so no steam escapes. Four hours for a 2kg lamb shoulder, five to six for pork shoulder, longer for anything larger. Under the foil the joint is effectively braising in its own moisture, which is what keeps the outside edible over such a long cook.
5. Take it well past 'cooked'.Probe the thickest part away from the bone. You are looking for roughly 90–95°C. Every doneness chart you have seen tops out at about 75°C; those apply to joints you intend to slice. Here you want the connective tissue gone, and that only happens above about 85°C given hours.
6. Uncover and brown at the end.Take the foil off, turn the oven to 200–220°C, and give it 20–30 minutes to colour and crisp the fat cap. Baste once with the pan juices as you do it. Pork skin will not become proper crackling this way — if you want crackling, remove the skin at the start and roast it separately on a tray at high heat.
7. Rest, then pull or spoon it apart.Rest 20–30 minutes. Do not try to carve slices — the whole point is that it will not hold together. Pull the bones out, which should come away clean, and take the meat apart in large forkfuls. Skim the fat off the juices and use the rest as gravy.

Tips

• This is the easiest large roast to time for guests, because thirty minutes either way makes no difference. That flexibility is a genuine reason to choose it over a leg.
• Half a shoulder works just as well and cooks in about two-thirds of the time. Ask for the blade end if you want the meatier half.
• Boned and rolled shoulder is fine but cooks slightly faster and less evenly than bone-in, and you lose the clean-bone signal that tells you it is ready.
• The juices under a slow-roast shoulder are the best gravy base you will get. Do not throw them out with the fat.

Common mistakes

• Applying a per-kilo roasting time — Those charts assume you want the middle at 55–75°C. A slow-roast shoulder is a different destination entirely and the charts will have you serving it three hours early.
• Roasting it uncovered the whole way — Five hours of dry heat on an exposed surface gives you a hard grey crust an inch thick. The foil is doing real work.
• Expecting crackling from a slow-roast pork shoulder — Crackling needs high dry heat. At 150°C the skin hydrates and goes leathery. Take it off and roast it separately.

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