Sous Vide – A beginner’s guide.

What is sous vide

At it’s heart, sous vide is slow cooking on steroids. You set the cooking temperature to exactly what you want the food item to reach. Place the food in the cooking container and wait. It is the exact opposite of pressure-cooking which raises the temperature to insane levels and blasts away so food cooks very quickly.

I have heard sous vide described as expensive “boil in the bag” cooking. That is like saying that a formula one racing car is just the same as a go kart.

The term is French and means “Under vacuum”. This reflects its origins in high end restaurants. However the vacuum is not important. The precise cooking temperature is.

What sous vide and pressure cooking share is an enmity for air. Air is the enemy of cooking. It is an excellent insulator and whenever it is present it slows cooking down. A pressure cooker replaces the air with steam. - or water. It depends on whether you submerge what you are cooking or not - very hot steam. As a result cooking efficiency is greatly increased. Sous vide replaces the air with, well, nothing. And you cook in water. Lots of water. Water is both an excellent thermal conductor and an excellent heat repository. But it is also an excellent solvent. So it will leech away the flavour in your food if you are not careful. So we place the food in some sort of container so we don’t lose the flavour.

Pressure cooking also leeches away flavour, but the amount of water is much less, and you frequently consume the water as part of the meal so it matters far less. By this time the water is called sauce so we don’t generally notice. At times, we throw away the food and just have the water. We call it soup or broth then.

Why sous vide

Sous vide gives you control.

Typically when you cook a steak, you place it on a ridiculously hot surface, watch it like a hawk, flipping it regularly (or not depending on what school of cooking you went to) in a usually vain attempt to prevent the outside from turning to ash before the inside has reached an acceptable level of doneness. There will always be a gradient from overcooked on the surface to almost raw in the middle. If you dislike raw, you will cook “Well done” (a misnomer if ever I heard one). And eat a dry, tough piece of shoe leather that used to be a wonderful piece of meat. If you shy away from dry and tough, you will cook rare, or even “bleu” and ignore the aghast stares of your fellow diners. And often eat a piece of meat that is tough because it hasn’t really been cooked enough. But it will be juicy. I must admit I fall into the latter camp. But the truly perfect piece of steak lies somewhere in the middle. The “well doners” may find a thin strip of it right in the middle of their steak. The “rarers” will find it closer to the edge. But in both cases, it will only be a small fraction of the whole

A better way to cook steak conventionally is to cook it “under” then let it rest while the overheated outside relinquishes some of its heat to the middle, cooking it further, and the protected middle gives up some of its moisture to the dry outer layers, moistening them and making them more palatable.

Sous vide blows this wide open. Because you are cooking at a precise temperature, you can achieve the perfect level of doneness – and therefore moisture, flavour and tenderness edge to edge. Further because, while cooking is a function of both temperature and time, the spot temperature defines doneness, the time it cooks is no longer critical. A steak cooked perfectly medium rare in half an hour will still be perfectly medium rare an hour later. This is very handy for the restaurant trade as they can get steak to the table quicker and more consistently. It is also handy for the home cook. That last minute phone call will no longer ruin dinner. Nor will getting the timing wrong on the potatoes. Undercooked spuds are almost as unpleasant as overcooked steak.

Note that timing is not completely irrelevant. There will always be a minimum time. This is determined by physics and relates to the time it takes heat to get from the exterior to the middle of a food item. There will also be a maximum time. While the food will be perfectly cooked to the desired degree of doneness, chemical changes will still be going on. Albeit slowly. A common complaint about steak at restaurants is that it is “mushy”. This indicates that the food was probably cooked in the morning for evening service. A great pressure reliever for harried staff, but it will ruin the meal for the fussy eater.

This trait can be used to advantage. Tough cuts like gravy beef (boneless shin) and rib can be cooked medium rare, or even rare, then kept at temperature for days while the breakdown continues slowly, resulting in perfectly succulent rare short ribs.

How to Sous vide

It is really quite simple. Create an environment where the temperature is the same as you want the final product to reach. Place the food in it and wait.

The heat source

The easiest way to do this is to vacuum seal the food in a bag and place it in a water bath kept at a constant temperature by a bit of kit more suited to the laboratory than a kitchen, set a timer and wait. Incidentally, the heaters commonly used as dedicated sous vide machines started out in life as laboratory equipment. Because these are precision machines, they are expensive.

But it doesn’t have to be done that way. All you need is a way to exclude air so the heat transfer is good, and a way to maintain an accurate temperature.

At a minimum, you want an accurate thermometer and a heat source of some kind.

You can use an insulated cooler for a water bath. Just add water at the right temperature or a little higher to allow for the fact that it WILL lose heat slowly. You can even use the kitchen sink or your bath, though that would only be suitable for quick cooks. Though you could set up a system to replace the water regularly. Even just set the tap to the right temperature and leave it running. You would want some way to deal with the overflow if you did this.

For that matter you could even use your oven even without the water bath. It will take a lot longer this way, and in this case the container will be to prevent drying out rather flavour leeching out.

The food container

Essentially what you are trying to achieve here is to keep the water and the food apart, while keeping as good a thermal contact as possible. Because air is an excellent insulator you want to exclude air as much as possible. The best way to do this is to use a large expensive chamber vacuum machine. This is simply not practical for most home cooks. Almost as good is a side vacuum machine often sold for packaging leftovers. These are both smaller and cheaper, but require expensive specialist bags, and are problematic when sealing liquids. But in the main they work really well. I use one of these.

Next down the pecking order is the humble ziplock bag. Put the food in, almost close it, and then submerge it almost to the top. This pushes most of the air out. Then fully seal and drop it in to cook. I would actually call this the perfect system as it is cheap, copes well with liquids, and does not squash delicate food items. The one downside is that the bags have a nasty habit of failing. When I use them, the common point of failure is that the seams give way. Higher quality bags have fewer problems, but I am yet to discover a brand that is faultless. I use them now and again for things I don’t want crushed. Higher temperature cooks are more problematic than low ones. So I never use them for vegetables thattypically need temperatures just below boiling.

The next to consider are jars. If you are cooking liquids, then a jar can often be the best bet. I use mason jars if I am cooking a crème bruleeor something in oil (confit). The liquid content means that air is not going to be an issue anyway, and the lid keeps the water out.

Also eggs already come with their own sous vide packaging. And if your meat comes vacuum sealed you can just put it straight in the water bath unless you want to add flavourings.

Specialist Kit

Once you have played around with improvised systems and have discovered you want to explore further, you will want to invest in a specialist machine. There are two basic types: Water bath and circulator.

Waterbath

This is a box with a tub for water, a heater and a temperature controller. They were the first type to hit the domestic market, but they have two problems:1. They are big. They are not easy to fill, empty and store. 2. They (mostly) rely on natural convection to keep the water at the correct temperature. This means they can develop hot and cold spots and will only be truly accurate where the temperature probe is.

They are increasingly being built into multifunction cookers. But the downside of that is that when you are cooking sous vide, you cannot use it to pressure cook or whatever. And as a sous vide will rarely cook a complete meal, you will usually want another bit of kit operating at the same time.

Circulator

These are a stick or wand that contains a heater, a temperature controller and a water stirrer. You supply your own water bath. Because they actively circulate the water, they tend to keep the temperature correct throughout the bath. Also, because you can use them with your own pot, storage is much less of an issue. This type is my preference. The container can be anything you want within reason. These days I generally use one in a beer cooler as that keeps the temperature even more even, and reduces the running costs. But I have used one in a saucepan (one litre is about the minimum practical size with my units), a stockpot, a pressure cooker, and even the kitchen sink when cooking for a crowd.

Extra stuff

Searing device

One thing sous vide won’t do is brown the surface of whatever you are cooking. Often it doesn’t matter, and may even be an improvement. I never sear fish for example. I tend to have it skinless and cover it with a sauce anyway so it really doesn’t matter. But, however well cooked it may be, a pink steak on the plate just looks wrong. And it is missing those Maillard flavours that are so important to a steak. So I sear some things. Options include a griller (broiler) in an oven, a frypan and a blowtorch. I prefer the last option. It is great theatre. And its intense heat quickly browns the exterior without appreciably cooking the interior any more. You can sear before or after cooking. After experimenting I prefer doing both. The before sear adds more flavour. The after sear dries the surface and adds a crispnessto edges you otherwise miss out on.

A rack

Not important when cooking one or two items, but when cooking more it helps keep the individual parcels separate to allow free circulation around them. I use a pot lid stacker from IKEA. There are lots of other options.

Insulating balls

By no means a necessity, these float on the surface of the water and prevent both evaporation and heat loss. So you need to top up less (or not at all) during a long cook and you use less electricity for all cooks.Ping-pong balls work, but tend to have a short life. Plastic film over the top also works but is single use can be quite fiddly. And there is quite enough plastic waste with the bags as it is.

Plate warmer

Because food coming out of a sous vide is at final cooked temperature, it can cool quite quickly. You really want to warm the plates. In winter I just put them on top of our fireplace. In summer, I will often put them in the oven on very low. Or even just drop them in the waterbath for a few minutes.