By Thomas Keller |
Sous-vide cooking is one of the most important new tools to enter the restaurant kitchen in the last 100 years, but because of the expensive equipment required, until now it's been out of reach of most home cooks. But if ... Read more
Step 1Trim any excess fat and sinew from the duck breast. Using a very sharp knife, lightly score the skin in a crosshatch pattern with lines spaced approximately one-fourth inch apart. Season with a pinch of salt.
Step 2Set up a work space as per the folded wrapping instructions at left. Carefully fold up the duck breast taking time to ensure that all the air is pushed out of the packet. Repeat and secure ends with tape. Cook for 35 minutes in a water bath at 140 degrees.
Step 3Remove from the water and allow the duck to rest for 5 minutes. Remove the breast from the plastic and dry the skin. In a non-stick pan heated over medium heat until hot, add a light film of oil and when the oil is hot but not smoking cook the breast skin-side down to render out some of the fat and crisp the skin. Rest briefly, then slice and serve.
By Thomas Keller |
Sous-vide cooking is one of the most important new tools to enter the restaurant kitchen in the last 100 years, but because of the expensive equipment required, until now it's been out of reach of most home cooks. But if you have heavy-duty plastic wrap, a big cooler chest and an accurate probe thermometer, you can try it.
Technology has taken hold in modern restaurant kitchens because it is based on a simple and fundamental idea: precision cooking of foods at carefully selected temperatures for precise lengths of time.
Most of the time in the kitchen, there is a great difference between the temperature at which we're cooking the food and the desired final temperature of that food. We may want a piece of lamb to be perfectly medium-rare at 139 degrees, but we cook it in a 400-degree oven. The result is vastly different degrees of doneness between the surface of the meat and its center. Furthermore, because the oven temperature is so high, if you leave in the lamb for too long, it will overcook.
With sous-vide, you cook food in a water bath that is at the desired final temperature of the meat. The water bath for that piece of lamb will be 139 degrees, so it will have exactly the same degree of doneness from the outer surface all the way to the center.
Cooking this way also vastly reduces the likelihood that something will be overdone.
As a bonus, cooking slowly in a tightly contained environment also helps food retain its natural juices and allows us to more effectively add flavorings.
While this accuracy can be liberating, I am always careful to emphasize -- particularly with our young cooks who have had access to precision cooking for their entire careers -- that sous-vide technology is not a replacement for traditional culinary knowledge. Rather, it is just another tool that educated cooks can add to their repertoires -- even in the home kitchen.
In the professional kitchen, we cook sous-vide by encasing food in airtight plastic using chamber vacuum sealers (hence the name sous-vide, literally "under pressure") and then cooking them in a precision-controlled water bath called an immersion circulator. Though these are now becoming available for home use, they are still quite expensive.
Rather than cooking the food using an immersion circulator, you can achieve similar results using a large picnic cooler and a probe thermometer.
Here's how you do it: Fill the cooler with hot tap water to preheat for 10 minutes and then drain. On the stove, bring water to the desired cooking temperature (you'll probably need to fill a couple of stockpots). Then transfer enough hot water to the cooler to fill it nearly to the top, reserving some water for later temperature adjustments.
Add the food and then check the temperature of the water and adjust as needed. If the temperature is too high, pour in a little cold water. If it's too low, add in some of the reserved hot. A good-sized, well-insulated picnic cooler with its lid on (we use a 28-quart picnic cooler) should maintain an even temperature for around one hour. For slightly longer cooking times, check the temperature periodically and adjust with fresh hot water as needed.
For even longer cooking times, you can use a pot of water on the stove, though it will be more challenging to control the temperature. If you do elect to cook on the stove top, keep in mind that a larger body of water will maintain a steadier temperature, so select a pot that is large enough for the meat you're cooking and an ample amount of liquid. Depending on how much control you have over the burners on your range, you may want to purchase a tool called a diffuser from your local kitchen store to provide separation between the pot and burner, making it easier to keep your water at a sufficiently low temperature.
Because cooking this way doesn't get meat hot enough to brown, you can sear it on the stove before or after cooking. The choice is up to you, but remember that any time you want a crisp skin (such as with duck), it should be seared afterward.
In place of the chamber vacuum sealer, you can get much the same result by wrapping the food tightly in plastic wrap, or sealing it in a food storage bag. Whichever you choose, be sure the plastic wrap or bag is certified food-safe well above the temperature at which you'll be cooking.
Always remember the absolute importance of time and temperature. The times and temperatures used in these recipes are accurate based on the size and cuts of meat we called for. Particularly when rolling food in plastic, the diameter of the finished cylinder will be the deciding factor in the time, but for temperature you can rely on a variety of printed and online resources.
Such guidance will give you an excellent starting point, but determining the ideal intersection of time and temperature for any recipe will remain the responsibility of you, the chef.
The home approach to sous-vide
How to keep shape, size consistent
There's more to sealing meat for sous-vide cooking than throwing it in a plastic bag. Because uniform heating is so important in sous-vide cooking, you need to make sure the meat is a consistent shape and size. There are several ways to accomplish this.
Rolling in plastic
One approach is to roll the ingredient you're going to cook into a cylinder using food-grade plastic wrap. Start by clearing a level, smooth work space that allows for an 18-by-24-inch sheet of plastic. Soak a kitchen towel in water and then wring it out so that it is just damp, and then use that to dampen the work surface -- this will help the plastic adhere.
Stretch a sheet of 18-inch-wide plastic wrap toward the edge of the table so that it hangs over the edge by about 5 inches and cut it from the box -- the sheet should be oriented lengthwise so that it stretches 24 inches away from you. Using a dry towel and working from the center, push out any air pockets from under the plastic wrap (a credit card or other stiff but flexible card works well too). Fold the very top edge of the plastic wrap over a few times -- this will create a tab that is easy to find for removal after cooking.
Before rolling, allow the meat to temper to room temperature -- something taken directly from the refrigerator will drop the temperature of the water bath below where you want it to be. Place the meat or fish to be rolled about 2 inches back from the edge of the table and fold the plastic over -- there should be enough plastic to cover the meat and still leave an overlap of 2 or more inches.
Wrap both hands over the meat and, using your fingertips to secure the plastic, pull back firmly to tighten the meat into a cylindrical shape (if the plastic slips it's because the workspace is too wet -- dry it off and start again). Maintaining tension and smoothing the plastic outward to remove any air bubbles, roll the meat all the way to the end of the piece of plastic wrap.
Pinch either end of the cylinder and, using gentle pressure to create traction, roll the meat away from you on the counter to tighten the cylinder and create plastic wrap "ropes" on either end of the shape. Pull to stretch the ropes apart -- this will tighten the cylinder and create additional pressure. Tie off one end as tightly as possible, pushing the knot down into the meat to secure the shape. Ensure that the other side is still tight -- rolling additionally if needed -- and then repeat. Trim to about 1 inch of plastic wrap rope on either end. If air bubbles are visible, eliminate them by poking a needle through the plastic.
Fold flat in wrap
To maintain the flat shape of a piece of meat, you can follow the same procedure up to the point where you place the meat on the plastic. At that point, rather than rolling the meat, fold the plastic over it and pull back with your fingertips to tighten. Continue folding the meat in the remaining plastic, smoothing any air bubbles out toward the ends after each fold. When you've used the whole sheet of plastic, fold the ends of the plastic wrap under and pull tight to seal the package. Repeat the process with a second sheet of plastic to seal the package even more tightly (you can use less plastic on the second time -- just enough to seal the ends of the first wrap). Again fold the ends under and then secure it with tape.
Zip bag and liquid
For pieces of meat that are unevenly shaped, use a zip bag. Make sure it is labeled either heavy duty or freezer-grade. Though these bags are convenient, it is very difficult to remove enough air to ensure even and efficient cooking. So instead add an additional cooking medium (for example oil or flavored liquid) to facilitate the transfer of heat from the water bath. Place the meat and any flavorings flat at the bottom of a bag that is about twice the size of what you're cooking. Add enough oil, melted butter or other liquid to cover the ingredients and then carefully flatten the bag until the liquid reaches the top and there are no air bubbles. Seal, fold over and secure the bag top with tape.
Zip bags are made from a plastic that has a softening point of 195 degrees, so if you use this method take great care not to pour boiling or near-boiling water into the water bath while it is cooking. If residual air pockets cause the bag to float after you've put it in the water bath, keep it submerged by laying a clean kitchen towel over the top.
-- Thomas Keller
Here's how to shape a sous-vide chicken breast into a cylinder for even cooking
- FOLD IT: Several thicknesses of plastic wrap along the top will make the sheet easier to handle.
- WRAP IT: Fold the plastic wrap over the chicken breast to encase it thoroughly.
- SHAPE IT: Use both hands to form the chicken breast into a cylinder inside the plastic wrap.
- KNOT IT: Finally, tie off both ends close against the breast to complete the seal.
The recipes here are written for only one portion in order to demonstrate technique and timing. You can cook as many as six pieces quite easily in the same-size water bath without too much trouble if you'll check to make sure the temperature hasn't dropped too much (just add more hot water if it has). For cooking more pieces than that, you'll need to check the temperature frequently early on to maintain even heat. Serve these meats with the accompaniments of your choice.