Cooking Tips

Butterflied Leg of Lamb

One of the most popular outdoor summer meals from the barbecue is butterflied leg of lamb, nicely browned and crusty on the outside, pink and juicy in the middle.

When the leg of lamb is ‘slash-boned’ (the opposite of tunnel-boned) and opened out, it cooks much more quickly than the full leg on the bone. But the leg with bones removed, and each sub-primal intact, is not even in thickness so it cooks a little unevenly; the thickest parts - the topside and thick flank - take longer to cook than the thinner parts. This can be an advantage to the cook who wants to serve some meat rare, some medium or well done. But if the aim is to produce evenly rare or pink meat throughout, it is best to cut the lamb before cooking to make it as even in thickness as possible. This is done by further butterfly-cutting the topside and thick flank.

Butterflying a Leg of Lamb

Your butcher can do this for you, but it is simple to do yourself if you use a sharp boning knife. To slash-bone the leg, begin at the tail bone end (the tail bone has usually been removed by the butcher).

  • Remove the aitch bone - Your aim is to first free the meat around the irregular part A of the aitch bone, then around the hip joint. Use the tip of your knife to sever the ball and socket joint B so you can free and move the aitch bone slightly away from the femur. Work closely around the aitch bone, back to the tail bone end, being careful not to slash into the meat. Remove aitch bone.
  • Remove the femur bone - With the tip of your knife mark a straight line from knee cap C to the ball end of the femur B. Now cut down into the meat along this line, until you touch the femur bone. Open the meat up along the length of the bone to expose the femur, stroking your knife closely along the bone at all times. Free the meat from the knee cap C and knuckle joint.
  • Remove the shank bone - Continue cutting close to the shank bone down its length. Remove femur and shank bone together. You now have a slash-boned leg.
  • Then - Lay the slash-boned leg of lamb out flat, skin side down. Using a large knife, start from the inner side of the thickest part of the leg (the topside) and make a horizontal cut through the middle of it, taking your knife almost to the outer edge. Fold the top flap out flat (like opening a book). Do the same with the other thick part of the leg (the thick flank). Trim away any fat pockets on the boned side, including the greyish popliteal gland in the silverside/shank region, but leave a thin fat cover on the skin side. Try to leave skin intact. Tidy up the shank end.

The Bone Structure of the Lamb Leg


Boned Leg of Lamb, Slash-boned


Boned, Butterflied Leg of Lamb

Cooking the Butterflied Leg

The flat boned leg can be roasted on a rack at a moderate or high temperature, or barbecued or grilled.

Suggested Flavourings

First marinate, season or flavour the lamb as you wish. Try the following:

  • A combination of rosemary or garlic oil, soy sauce, lemon juice, pepper and pomegranate molasses or spicy apricot sauce
  • Crushed garlic, grated fresh ginger, lemon rind and juice, teriyaki marinade or light soy sauce, pepper
  • Crushed garlic, ground coriander, cumin, pepper, olive oil, honey, lemon juice, sweet chilli sauce

To roast - Place the leg, cut side up, on a rack in a roasting pan. Fan-bake at 180° to 200°C for 15 minutes. Turn lamb skin side uppermost and fan-bake for approximately 15 more minutes, to the desired degree of pinkness. Allow at least 20 minutes resting before carving.

To barbeque - For ease of handling on the barbecue, run two or three lasrge metal skewers horizontally through the leg before cooking. Barbecue the lamb over steady, low heat, turning it every 10 minutes or so, basting if you wish. A small leg may need 30 to 35 minutes, a larger, thicker leg, up to 40 or 45 minutes. Do not overcook, and remember to allow plenty of resting time before carving.

Hints from a Chef

Use a dry herb or spice rub to flavour this versatile piece of meat. However, be careful of the risk of burning dry flavouring ingredients left on the outside of the meat when grilling, frying or barbecue cooking. For these cooking methods, use a wet marinade that can be drained off before coking. A dry herb/spice rub can have a little oil mixed in, or the spice-rubbed meat can be brushed with oil just before cooking. A totally dry flavouring rub is best used when cooking time is longer and in dry heat, such as roasting.


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