I love a good roast lamb (proof). Here’s my classic recipe for lamb leg, rubbed with garlic and rosemary, served with gravy, peas, carrots and crispy roast potatoes (duck fat or classic). I hope you love it as much as I do!
The only thing you need to know for perfect roast lamb leg
I have a lot to say about roasting any kind of meat. Especially Australia’s favourite roast – the great lamb leg. But there’s really only one thing you need to know to make perfect roast lamb leg, every single time:
GET A MEAT THERMOMETER!!
It’s the only way you can take the guesswork out of cooking lamb leg so it’s perfect blushing pink and ridiculously juicy inside. Because – and here’s something Aussies don’t like to talk about – lamb leg is actually very lean so if it’s not pink, it’s dry. Full stop, end of story!
My meat thermometer – For most of my adult life, I was using a $5 thermometer I got on Ebay which never failed me. A few years ago I finally decided it was time to invest in a real one so I got a Thermapen which is pretty well regarded as the best (my thoughts here). Even if you can’t invest in a Thermapen – it’s the 21st century, and even cheap tech isn’t so bad. Invest in a $5 meat thermometer. That’s a lot cheaper than a wasted, overcooked lamb leg!
OK, I do have a few more “how to make the perfect roast lamb leg” tips!
Garlic rosemary rub – classic lamb flavours.
Start on high to get the colour going then lower heat.
Roast on a bed of garlic (or onion).
Make the gravy using the pan drippings. Roast lamb gravy is better than every other cut of meat – beef, chicken, pork, none of them compare!
What you need for roast lamb leg
Starting with the hero ingredient – the lamb leg! Get the best you can afford – yes, meat is like wine, the more you pay, the better the quality. Quality of life of the animal also comes into play there.
All that red ink you see is perfectly safe to eat and actually, you only see it on better quality lamb. You don’t typically see it on supermarket lamb.
Cut bone – Some (most?) butchers and almost all supermarkets sell lamb leg with the shank (bone) cut. Either fully cut off or partially cut so it folds. This is simply for practical reasons – shelf storage and packing space. For grandness, I like the bone in tact. But it doesn’t matter ,it’s purely a visual decision!
Rub for roast lamb leg
Here’s what you need for the rub: rosemary, garlic, olive oil, salt and pepper. Use fresh rosemary – dried is not the same!
Roast lamb gravy
All you need for gravy is flour for thickening and beef stock/broth for the liquid. You shouldn’t need extra salt for the gravy. I find the salt on the lamb that ends up in the pan drippings plus the salt in the beef stock is enough. But taste and add more if you want!
Why beef rather than lamb stock? Well, there’s a reason lamb stock is not typically sold at grocery stores! It’s just very…lamby. 🙂 Beef has a cleaner flavour. It doesn’t make the gravy taste beefy at all because there is so much lamb flavour from the drippings.
Why not chicken stock? It works fine but the gravy colour is paler. I like my gravy for roast lamb leg to be a really deep brown colour!
How to make roast lamb leg
Rub with rosemary and garlic, roast in a hot oven to get the colour going then continue at a lower temperature for 1 hour or until the internal temperature is 53°C/127°F (for blushing pink perfection). Rest for 20 minutes before carving. It will still be very warm even after 1 hour – enough time to make duck fat potatoes!
The lamb leg pictured is a 2.75 kg lamb leg which is about the average size you get from good butchers. Supermarket lamb legs tend to be a little larger from slightly older animals which makes the meat a little less tender and a little stronger “lamby” flavour. Albeit, as you’d expect, cheaper than from butchers.
Make rub – Mix oil, garlic and rosemary in a bowl.
Rub then sprinkle – Slather the rub all over the lamb, then sprinkle the salt and pepper all over. It’s better to do it this way for more even dispersion of salt – if you put it in the oil, it doesn’t spread quite as evenly because it pools in the bottom of the bowl.
I do this rubbing step in the roasting pan – why dirty a cutting board??
Garlic bed – Place cut garlic and rosemary under the lamb.
Hot oven 20 minutes – Roast for 20 minutes in a hot 240°C/475°F (220°C fan) oven. This will get the colour going on the lamb. It’s tempting to go longer to get even more colour on it but I find if you go beyond 20 minutes you end up with too much overcooked meat “ring” on the outer edges of the lamb.
1 hour lower oven – Reduce heat to 200°C / 400°F (180°C fan) and roast for a further 1 hour or until the internal temperature of the lamb is 53°C/127°F for blushing pink perfection.
Check the internal temperature at the 45 minute mark. Never rely on a recipe cook time for roast meat, use your thermometer! So many variables can affect the exact roasting time, from oven strength to pan heat distribution, the shape of the lamb leg and how cold the meat is right in the middle.
See below for more information on lamb doneness and different size lambs.
Rest 20 minutes – Rest the lamb for 20 minutes before carving. During this resting stage, the lamb finishes cooking and the internal temperature will rise to 62°C/144°F which is perfect medium rare for lamb.
Also during resting, the lamb juices get re-absorbed by the meat fibres so when you cut into the meat, the juices remain in the meat and eventually end up in your mouth. If you do not rest the meat then the meat juices leak out everywhere when you start carving the lamb.
Internal temperature of roast lamb leg
No credible restaurant would ever serve lamb leg at anything over than medium rare! But I do know some people like their lamb done a little more, so here are the internal temperatures for lamb leg at different levels of doneness.
Take the lamb out when it hits the “temperature out of oven”. After resting for 20 minutes it will rise to your target level of doneness.
TIP: Take the lamb out early!!!
This is one of the most common mistakes people make when roasting lamb. If you want medium rare lamb and you take the lamb leg out of the oven when it hits 62°C/144°F (which is the medium rare target temperature), it will rise to 73°C/163°F once rested which is well done – no hint of pink at all! This occurs because the lamb continues to cook after you take it out of the oven due to residual heat. It’s called carry-over cooking.
So if you want medium rare, perfectly pink lamb leg, you need to take it out of the oven once the internal temperature reaches 53°C/127°F. At this temperature, the lamb is rare.
But when you rest the lamb for 20 minutes, it will continue to cook and the internal temperature will rise by 9°C/17°F to 62°C/144°F. This temperature is medium rare, the optimum doneness for lamb leg so it’s beautifully juicy. Any more and the lamb meat is drier than ideal, because lamb leg is a lean meat.
How to make gravy for roast lamb leg
Gravy for lamb leg is made using the pan drippings after roasting the lamb. “Drippings” simply refers to the fat and meat juices left in the roasting pan after roasting the meat and it’s our express, free path to a killer gravy.
Heat drippings & cook flour – Once you take the lamb out of the roasting pan, put it straight on the stove to heat the fat. Add flour and stir it for 1 minute to cook it off – it will kind of be like a paste.
Pour in the beef stock, stirring as you go to help dissolve the flour.
Smush the garlic with a potato masher or even a smooth to help release the beautiful caramelised garlic flesh into the gravy.
Strain – Then just simmer for a few minutes until the gravy thickens to your taste then strain into a bowl, pressing the gravy liquid out of the garlic heads. Then pour into a jug to serve!
And that, my friends, is everything you need to know to be the king (or queen) of roast lamb leg from this day forth. The precision by which you roast your lamb to blushing pink perfection will be admired. Your gravy will be whispered about in your circles – the flavour!!! It’s incredible!
Just smile sedately, sit back and bask in the praise. There is no need to reveal your recipe source. 😎
The lamb leg in this post is pictured with duck fat potatoes (the best crispy potatoes in the world!) with peas and steamed carrots tossed with a little butter and parsley. If you don’t have duck fat, make my classic crunchy roast potatoes instead. They are still way crunchier than your usual way of making them.
Go forth and enjoy your new lamb-alicious world! If you’ve got your own lamb leg secrets, sharing in the comments below – readers love hearing what you have to say. – Nagi x
Watch how to make it
Roast Lamb Leg with Gravy
- 2.75 – 3 kg / 5.5 – 6 lb lamb leg , bone-in (Note 1)
- 1 1/2 tsp cooking salt
- 1/2 tsp black pepper
- 1 1/2 tbsp fresh rosemary leaves , finely chopped
- 3 garlic cloves , finely minced
- 2 tbsp olive oil
- 2 whole heads of garlic , halved horizontally (Note 2)
- Few sprigs rosemary (optional)
- 4 tbsp flour , plain/all purpose
- 2 1/2 cups beef broth / stock , low sodium (Note 3)
- Take lamb out of fridge at least 1 hour before roasting. (Note 4)
- Preheat oven to 240°C/475°F (220°C fan) with oven shelf in the middle.
- Rub – Mix rosemary, garlic and olive oil.
- Prepare lamb – Place lamb leg in a roasting pan. Coat with the rub using your hands, the sprinkle with the salt and pepper. Place garlic and rosemary sprigs underneath the lamb, garlic cut face up.
- Roast lamb leg for 20 minutes. Turn the oven down to 200°C/400°F (180°C fan) and roast for a further 1 hour or until the internal temperature reaches 53°C/127°F for medium rare (Note 5 other doneness). Check first at 45 minutes – everyone's oven is different!
- Rest – Remove lamb from oven. Transfer lamb to plate, loosely cover with foil and rest for 20 minutes to 1 hour (it will still be warm enough for serving!). The internal temperature will rise to 62°C/144°F (medium rare). Make gravy while lamb is resting – below.
Gravy for roast lamb leg
- Drippings in pan – Discard rosemary sprigs. You should have around 4 – 5 tbsp of fat (drippings). If less, add butter. If much more, discard a bit.
- Add flour – Place roasting pan on stove over medium heat. When the fat starts to bubble, then add flour. Mix flour in and cook for 1 minute.
- Stock – Pour in half the beef stock and mix to dissolve sludge in, then add remaining beef stock and mix.
- Garlic squidging – Use a potato masher (if you're really keen like me) to mush the garlic to squeeze out the flavour (also helps flour caught in garlic to dissolve).
- Taste – Check salt and pepper (I don't add more).
- Thicken – Simmer for a couple of minutes, stirring, until it starts to thicken. Take it off the stove BEFORE the gravy is the thickness you want because it will keep thickening.
- Strain into a bowl, mushing garlic to squeeze all the liquid out. Then pour into gravy jug and serve with lamb!
Originally published October 2016. I have been very neglectful not updating one of my favourite recipes with sparkling new photos and a recipe video!
I told you – I LOVE roast lamb! See?
Life of Dozer
Original photo from when I first published this recipe in 2016 still holds true, so no need to update:
DOZER. Don’t breathe your stinky dog breath over my friends while they eat!