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Sous Vide: Boneless Leg of Lamb

Leg of lamb benefits especially well from sous vide processing, as the low temperature treatment prevents the all too frequent scorching,

Ingredients

Lamb leg, boned, rolled and tied, one each. Australian and New Zealand legs are usually about 5 lbs/2.5 Kg, while the American versions may run considerably larger. The time/temperature parameters remain the same.

Kosher salt, 1 Tablespoon/Kg (about a teaspoon per pound).
Cayenne pepper, 0.5 teaspoons/Kg, (about a pinch per pound).
Egg whites, 1 each, beaten.

Leafy green paste/chimichurri/pesto:
Baby kale, baby spinach, baby chard, 1 oz.
Note: This product is usually nicknamed “power greens” or some other proprietary buzzword, but any bitter leafy green will work–arugula, basil, etc.
Garlic, fresh, one head, peeled.
Kosher salt, a pinch.
Olive or vegetable oil, 4 oz/100 ml.

Sous Vide/Roasted Root Vegetables (optional)
Carrot, one each, peeled.
Parsnip, one each, peeled.
Potato, one each, peeled.
Sweet potato, one each, peeled.
Garlic, one head, peeled.
Kosher salt, to taste.
Vegetable oil, 2 oz/50 ml.

Equipment requirements

Immersion circulator, portable or stationary.
Heat rated container, minimum of 2 gallons/8 liters.
Heat rated sous vide bags.
Channel or chamber vacuum device
Pastry brush.
12″/300 mm skillet or oven.
Propane torch (optional).

 

How do you like your leg of lamb?

There is debate as to the exact definition of “rare,” “medium rare,” “au point,” etc. A little practice will help you learn just exactly what temperature achieves your preferred appearance of doneness.

Here are some basic temperature setting guidelines:

Rare: 129 F/54 C.
Medium rare: 135 F/57 C
Medium to Medium well: 140 F/60 C.
Well done: 150 F/74 C.

When guests in restaurants and hotels specify their preference for appearance of doneness, the chef will add heat to individual orders, hopefully achieving the desired level of doneness. This is usually done by dipping the individual cut in stock or broth, aka “jus.” Exposure to hot liquids can cause the meat to “clinch,” so the jus should NEVER be hotter than 165 F/74 C.

Procedure:

Level of difficulty: 2.5

Preheat the water in your sous vide bath to the temperature that most closely matches your preference. We will exhibit the results of two different temperatures, which we will note on each picture.

Let sous vide timing work for you!

Among sous vide’s several unique characteristics, cooking time is determined by the shortest distance from the surface of the roast to the geometric center instead of by weight. Many newcomers are daunted at first by what appears to be an inconveniently long period of time required to sous vide process proteins.
The fact is, the rate of collagen conversion in this range of temperatures is very gradual. This means that the texture and appearance of a roast processed for 8 hours will differ only slightly, if at all, from a roast that has been processed for 16 hours. Some people want to start their roast in the early morning to serve for dinner that evening, so the 8+ hour interval is convenient for them. Others  would rather start it the evening before and sleep in! Both approaches are favorable!

Norm’s sous vide/roasted vegetables

If you want to serve the roasted vegetables with your lamb, seal all of them EXCEPT THE GARLIC in one or two vacuum bags and process in a sous vide bath at 183 F/84 CX1 hour. Shock the package(s) in ice water until they achieve a maximum of 70 F/21 C. You can refrigerate until a later date, or continue the preparation so you can serve them with the lamb:

After cooling the vegetables, cut them into uniform shapes–I like to carve them into ovals, but that is an old habit and not necessary. Large bite sized pieces work just fine!

One hour before service, preheat an oven to 400 F/204 C, toss the vegetables in the oil and salt, and roast until brown. When they are almost done, add the garlic and roast until lightly browned. They can be kept in a warming oven until service, or even reheated in a microwave oven–there is no shame in using a microwave oven!

Processing the roast

After vacuum sealing the leg of lamb, process at the appropriate temperature for

8-16 hours, as per your convenience and regardless of the size.

Make the drizzle

While you are waiting for the lamb, make the leafy green paste–my friends laugh at me when I call it pesto and it would not be fair to call it chimichurri. Assemble all the ingredients except the oil and process in a generic blender or small food processor. Slowly drizzle the oil as if you are making an emulsion, but this product will not really emulsify like aioli. Of course, neither will pesto or chimichurri. Set aside. I like to keep it in a squirt bottle.

Back to the roast

When the chosen time has elapsed, remove the roast from the bath and set on a flat surface with a rim to collect any juices from the bag. Remove the roast from the bag and set on a clean towel. Harvest the juices and save for later use. This is explained HERE.

Pat the roast dry with a clean towel. Use pastry brush to paint with the beaten egg whites; sprinkle the kosher salt and cayenne pepper. The roast below was processed at

129 F/54 C for 12 hours

Heat a large skillet to 275 F/135 C, add the vegetable oil to the pan an lay the roast in. You should hear sizzling, and maybe even a little spitting. If you hear popping, reduce the heat!

Increase the heat slowly as you brown the roast and roll to continue browning on all sides.

The roast will have a tendency to capsize, so…

Lean it against the rim of the pan to prevent this.

Even the finest of pans and the most expensive of stoves will not heat evenly, so rotate the actual pan to make sure the roast is on a hot spot.

Continue browning until a crust forms all around the roast–this should take about five minutes.

Remove the roast to a platter or suitable work surface. You may notice that you missed a spot here and there–this is where a propane torch comes in handy!

Do not attempt to remove the string intact–use scissors to cut it off. This may also remove a little bit of the crust–the cost of doing business. Use the torch to sear as needed–no one will be the wiser! The roast below was also processed at 129 F/54 C.

This makes a festive presentation, and it’s great for taking pictures. One wonders how the carving might be continued at the table without making a gigantic mess, so I usually carve and plate in the kitchen. Here is an example served with assorted vegetables, a bell pepper brochette, and the pesto described in the ingredients section. There are also a few drops of a natural gravy made from juices from the bag after they were filtered with a little demi-glace. On the right hand side is a small pool of rosemary gastrique. The picture below was processed at

132 F/55 C.

After years of friendship, you learn who likes their sauces on the side and how people like their lamb cooked–some prefer their lamb to be rare just like many people like their beef. This lamb was processed at

129 F/54 C for 12 hours

When I worked in hotels, most people ordered their lamb “medium,” but, honestly, without sous vide, it is difficult to cook a lamb leg to 129 F/54 C, and usually ends up getting served well done. People rarely object to this, unlike they might if they ordered Prime rib. Here is a plattered leg that we processed at 140F/60C:

Whatever you do, and however you serve your lamb, remember that I said ENJOY!

Norm King

 

 

 

 

 

About

Even though we like to call it "Spring Lamb," anyone who has seen "that movie" knows that sheep are born in the spring and slaughtered in the fall. The seasons in the southern hemisphere are reversed from ours, so lamb's availability is no longer limited to one season or another. Australia and New Zealand are producing a high quality product, somewhat smaller than their American cousins but equally wholesome and delicious.
This recipe departs somewhat from the traditional rosemary/mint version by substituting an Argentine inspired pesto with baby kale, spinach, and chard. We will not call it chimichurri, although the comparison is unavoidable. Roasted root vegetables appear around the edges.

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