How do I cook a rack of lamb?

A rack is the loin still attached to its ribs — the same muscle as a lamb chop, in one piece. It is lean, tender, small and costly, which makes it the least forgiving lamb joint in the shop. Everything about the method exists to control a very short cooking window.

What you'll need

• A rack of lamb, French-trimmed
• An instant-read thermometer
• An ovenproof frying pan
• Mustard and breadcrumbs if you want a herb crust

Step by step

1. Bring it up from fridge cold and dry it well.A rack is small enough that 30–40 minutes out of the fridge genuinely does even out the temperature gradient, unlike a large joint. Pat the fat cap completely dry — moisture there stops it browning.
2. Score the fat and render it in a dry pan.Cut a shallow diamond pattern through the fat, not into the meat. Put the rack fat side down in a cold or barely warm dry pan and bring the heat up gradually. Give it five to eight minutes until a good amount of fat has run out and the surface is deep golden. Starting cold renders far more fat than dropping it into a hot pan.
3. Sear the ends and the meat side briefly.Thirty to sixty seconds a side. You are colouring, not cooking. Pour off the excess fat — keep it, it is excellent for roast potatoes.
4. Add a crust now if you want one.Brush the fat cap with mustard, press on a mix of breadcrumbs, parsley, garlic and a little melted butter. Do it after searing, or the crumbs burn. Wrap the exposed bones in foil if they are browning too fast.
5. Roast fat side up at 200°C and probe early.12–20 minutes depending on the size of the rack and how many bones it has. Start checking at 10 minutes. Push the probe in horizontally from the end, along the eye of the meat, so the tip sits in the centre of the loin rather than passing through it.
6. Pull at 52–55°C for pink.Roughly 50–52°C for rare, 54–57°C for medium-rare to pink, 60°C and above for medium. Because the muscle is thin, carryover is quick and modest — expect around 2–4°C. Take it out at the lower end of your range.
7. Rest ten minutes, then cut between the bones.Rest fat side up on a warm plate. Cut down between each pair of bones for double cutlets, or between every bone for singles. Serve immediately — lamb fat congeals fast on a cold plate.

Tips

• Ask the butcher to French-trim it if it is not already. Supermarket racks usually are; the exposed bones look better and stop the thin end overcooking.
• Two racks interlocked into a guard of honour cook slightly slower than one flat rack because the meat faces inwards. Add a few minutes and probe.
• The rendered fat is the best thing about cooking a rack. Save it for potatoes.
• If the crust is browning before the meat is up to temperature, drop the oven to 180°C rather than covering the crust, which softens it.

Common mistakes

• Searing the fat cap in a screaming hot pan — The outside blackens before the fat underneath has rendered, so you get a burnt surface over a soft white fat layer. A gradual start renders it properly.
• Roasting by time alone — Racks vary from four to eight bones and from slim to thick. On a joint that cooks in fifteen minutes, a two-minute error is visible on the plate.
• Cutting into it to check — It is too small to lose juice from. A probe reads the centre without opening it.

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