Foods & cuts · Lamb

Butterflied leg of lamb

A leg with the bone out and the meat opened flat. Its uneven thickness is usually described as the problem with it, and is better understood as the point of it.

What it is

Form: Boneless joint
Typical weight: 1500–2500 g
Typical thickness: 25–70 mm
Cut: Leg of lamb

Why it behaves as it does

Boning and opening a leg turns a thick, slow, awkward joint into something that fits on a barbecue and cooks in the time a party lasts. What it does not do is make it an even thickness — an opened leg runs from about 25 mm at the thin end to 70 mm at the thick, and no technique flattens that away. The useful reframing is that this gives you a range of doneness on one piece of meat, so a table with someone who wants it pink and someone who does not can be served from the same lamb. Position accordingly: thick end towards the hotter part of the fire, thin end away from it, and carve across the grain from the thin end inwards.

When is it done?

Food-safety endpoint

Food Standards Agency
The Food Standards Agency states that whole cuts of red meat such as steaks can be served pink, rare or bloody and will be safe to eat as long as the surface has been adequately seared. It gives no internal temperature for this case, so there is no figure here to cook to — the searing of the surface is the condition.
The rule and its source
In England, Wales and Northern Ireland the Food Standards Agency states that whole cuts of red meat such as steaks may be served pink, rare or bloody, on the condition that the surface has been adequately seared. No internal temperature is given for this case.
Well established
- Food Standards Agency — States this directly
  “red meat such as steaks can be served pink, rare or bloody and will be safe to eat as long as the surface has been adequately seared”
  What it covers:
  The document states its own reach: 'Applies to England, Northern Ireland and Wales'. Food Standards Scotland publishes separately and, as recorded separately, does not make this statement.
  The permission is CONDITIONAL and the condition is the whole rule: the surface must have been adequately seared, because on a whole cut the contamination is on the surface. A reading that drops the condition has changed the guidance into something else.
  Shape:
  No figure is given, and none is implied. This is a statement about a FORM rather than a temperature, which is why BBQHQ had to be able to record a rule about form at all before this could be held without inventing a number to hang it on.
  About this source · Original · retrieved 2026-08-14
USDA Food Safety and Inspection Service
In the United States, whole cuts of beef, pork, lamb and veal — steaks, chops and roasts — should reach 145 °F (63 °C), followed by a rest of at least three minutes before carving or eating.
- 63 °C (145 °F) — measured at the centre of the thickest part, away from bone and fat.
The rule and its source
In the United States, whole cuts of beef, pork, lamb and veal have a safe minimum internal temperature of 145 °F (63 °C), followed by a rest of at least three minutes.
Well established
- United States Department of Agriculture, Food Safety and Inspection Service — States this directly
  “Cook raw beef, pork, lamb and veal steaks, chops, and roasts to a minimum internal temperature of 145 °F ... allow meat to rest for at least three minutes”
  Form:
  Whole cuts only. Ground meats are covered by a separate, higher figure.
  The three-minute rest is part of the safety requirement, not only a quality step.
  How it was measured:
  As measured with a food thermometer before removing from the heat source.
  About this source · Original · retrieved 2026-08-13

When it goes wrong

It came out dry: The meat came out dry — 4 distinguishable causes.

Afterwards

Cooling, keeping and reheating what is left is general guidance for barbecue leftovers. Neither UK authority publishes anything specific to butterflied leg of lamb, and BBQHQ does not invent a distinction they do not make.