Reverse-seared Leg of Lamb: Temps and Technique

If you’re about to make the one lamb roast that most Americans make each year, you may be casting about, looking for tips. Well cool your heels—you’ve found the place. A lamb dinner is not something we all enjoy every week in this country (more’s the pity), so it’s not something most folks have practiced well. If you want the most perfect leg of lamb with the best chance for proper doneness, we recommend a reverse sear. Read on below to find out both how and why you should cook your lamb this way this year.

Lamb leg doneness: what is best?

Lamb is like beef, but turned up to 11. It has more flavor, it is more tender, it has all the same cuts (though some of them are tiny and hard to track down—get to know someone who raises lamb and/or a good butcher, and you may be able to score some), and it’s red meat. So we treat it basically like beef. If you don’t like that “lambiness” that it can have, you may be overcooking your meat, which makes that flavor more distinct, in much the same way that cooked salmon tastes more salmony than raw salmon on sushi does. Many people find they actually like their lamb a little rarer than they do their beef, but either way, medium rare is right where most people will like it. Aim for a final internal temp of 130–135°F (54–57°C), which means pulling it from the heat at about 10°F (6°C) below that. Use your RFX MEAT Wireless Meat Probe to monitor the roast’s internal temperature no matter where you are, and set the alarm in your app for your preferred pull temp.

How to get perfect doneness with a reverse sear

Keeping the meat from overcooking around the edges is a challenge, but it’s one we’ve faced before. In a high-temp cooking situation, the heat builds up in the outer inches of the meat so that by the time the thermal center gets to an appropriate pull temp, the outside is far overcooked.

So we should just cook it at a low, slow temperature, right? While that sounds like a good idea, it lacks one thing: crust. Meat tastes better when it is cooked hard on its surface. The complex chemical reactions known as Maillard browning create a multitude of flavor chemicals that make meat taste tasty. Without them, slow-cooked meat would taste no different from boiled meat. That’s why a sear is so important for chops, roasts, or even steaks.

And now we get to the crux of the issue—this is why the reverse sear is so useful. We can low/slow our initial cook, then let the roast cool a bit before we sear the outside over high, hard heat. We get the best of both worlds, but we do it with a much greater degree of control.

How we did our reverse sear

For our leg of lamb roast, we purchased a boneless leg, seasoned it inside and out, re-rolled and tied it, then put it in the smoker for our initial low-heat cook. We set our internal temp alarm with our RFX MEAT for 125°F (52°C). That temperature gave us room for about 10°F of carryover cooking, just like we want. We then ran our smoker at 250°F (121°C) for a good balance between flavor and speed. Of course, we verified the pull temp with our Thermapen ONE, making sure we actually hit the thermal center with our RFX MEAT probe.

After our alarm sounded, we took the leg of lamb out of the smoker and let it sit while our grill finished preheating. As soon as we had a ripping fire going, we put the roast on the grill and let it cook just until the outside was browned and tasty. By letting the meat cool somewhat before searing it and searing it so quickly, we avoided overcooking and ended up with delicious results!

A note on how to do this in the oven

We used a smoker and a grill, but there is no reason at all why you shouldn’t do this even if you don’t have a smoker. Cook your roast slowly in your oven, then sear it in a hot, heavy pan on the stove. Or, take it out of the oven and crank the heat up to 500°F (260°C), then, when the oven is preheated, put the roast back in and let it sear. Keep a close eye on it and take it out as soon as there is good browning on the surface. This takes longer than the pan sear, but is easier. You choose.

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A roast leg of lamb is a treat, and one that we should really be eating more frequently than we do as a country. But until we do, this is a dish that gets about as much practice as a Thanksgiving turkey! If you want to make sure you get it right, the reverse sear method—aided by RFX MEAT and your Thermapen ONE for your critical temps—is a fantastic way to make sure that everything goes the way you want. Give it a try this spring, and we’re sure you’ll love the results. Happy cooking!