The general process of sous vide cooking involves three general stages. Depending on your goals and tastes, each involves required and optional steps.
The most important thing to understand about sous vide is actually to first understand how difficult conventional cooking is. When you are preparing cold meat over a source of high heat, the window of time for ideal doneness is very short. Sous vide cooking uses low temperatures that also happen to be the final target temperature, so that same window is extended indefinitely.
Even when ignoring the more obvious consequences of undercooking or overcooking, the truth is that your food will always be cooked unevenly. Thinner parts of your chicken breast will be drier and the edges of your steak will always be tougher. This is not to say conventionally cooked foods are inferior to sous vide, but only that conventional cooking is much more difficult.
The idea beind sealing food for sous vide cooking might intimidate some, but it shouldn't. While there are expensive and fancy ways to go about it, most people choose one of two techniques. Do your best to seal your food, but as long as your food stays underwater, you are good to go.
It is tempting to think that seasoning food inside a sous vide bag will impart huge amounts of flavor, but it's often not the case. Sous vide cooking does a great job of bringing out the natural flavor of its foods, but is inconsistent with added seasoning. I have found that seasoning typically flavors the surface of meat well, but the inside significantly less so. For the fullest flavoring of your food, marinades or brines might be a needed step.
If you are planning on searing your food, I would say that applying your seasonings right before searing and serving is easiest and most effective. It is essentially seasoning your food in the same way you would if you were cooking conventionally, except with food that is more receptive to flavors.
If you are intent on adding seasonings before cooking, make sure not to combine fats with aromatics. The flavor of the herbs such as garlic or rosemary would be diluted into the added fat such as butter, creating a highly aromatic pool of fat, but less aromatic food. For even more flavor, some people also prefer toasting or roasting their aromatics to compensate for the low temperatures of sous vide cooking.
It is often hard to plan out your cooks to incorporate a marinade, but with some planning, its very easy to give some exciting flavors to your food.
I generally advocate to marinade your food for at least an hour for the best flavor, but especially for longer cooks over a few hours, it is not always necessary. Many times, the marinade can serve as a great glaze or sauce to serve your food with. For more marinade ideas, check out the ingredient time and temperature pages, but a typical marinade will consist of acid and flavoring elements, with oil as optional.
ACID (vinegar, wine, citrus, mirin)
FLAVORINGS (spices, herbs, umami sources such as soy sauce, miso)
FAT (oils, milk, yogurt)
A natural instinct is to assume the longer the marinating time, the better, but marinades with heavily reliant on acids or salt will negatively affect the texture of your food if marinated for longer than a few hours. Keep in mind that alcohol usually evaporates in the cooking process, but does not do so in the sous vide bag, so add less than you normally would.
Espcially for pork and fish, brining is a nice step you can take for increased tenderness and flavor. By putting your food into a salty environment for an extended period of time, the dissolved salt will loosen the protein bonds in your meat and allow the fibers to hold more moisture throughout the cooking process. While some recipes will call for a dry brine, I prefer wet brines because they require less salt.
There is no universal recipe for brines, but most hover around 5% salt content. In practical terms, this means about 50 grams of salt in a liter of water or 2 tablespoons of Morton's coarse kosher salt for every 2.5 cups. It's important to pay attention to the type of salt as their density and additives change the amount needed. While kosher salt is preferred, you can use reduce the amount by a third in order to adjust for using table salt.
You can use the brine to incorporate flavors besides salt. If you want to lessen the taste of salt, you can add sugar. A general ratio is 3 parts salt to 1 part sugar. Acidic liquids such as vinegar and citrus juices, oils, dried herbs and spices are popular choices as well.
There are a few possible pitfalls with brining. The first is brining for too long, which can turn meat overly salt. Most meats can brined anywhere from 2-12 hours, but fish is done in as little time as 10 minutes. The second is not rinsing the brine thoroughly enough. Running your food under cold running water for a minute or two should do the trick. If you are using a ziplock for the brine, people generally prefer not to use the same bag for cooking due to residual salt.
Lastly, you want to make sure the brine is thoroughly mixed and dissolved. While not always required, boiling the water and then allowing it to cool is the safest option, but it is definitely recommended with dried herbs and oils.
Similar to conventional oven cook times, there is no "perfect" time and temperature to cook foods at. Having seen some the all-in-one sous vide temperature apps and charts that are available, I have personally found having a variety of suggestions helps a lot in finding what works best for my tastes. Each page in the times and temperature section of this site will have suggested cook times and temperatures that are curated from all over the internet.
For longer cooks, I like using binder clips to keeping my bags in place and underwater. Having experimented with weighing the bags down with other tools, I have found that clipping my bags to the side of my stockpot keeps the the side of the bags rigid enough to stay where they should.
Even though they typically require longer cook times, I have personally found that I tend to prefer lower temperature settings, but your own experience may vary. According to Douglas Baldwin , most food pathogens stop growing at 126.1 F, so with fish as the major exception, most sous vide cooking is done at above 130 F. In general, sous vide temperatures outside chicken have some leeway into how medium rare or even rare you can cook to, so feel free to experiment.
For the of sake of safety, the cooking times on this site should be seen as minimum baselines and you might need to adjust for a slightly longer duration based on the thickness of your food and whether it is frozen or not. If you are trying to cook something especially thick, you can make sure it cooks in a normal amount of time by separating it into thinner portions. The general rule is if something is twice as thick as "normal", you should double the cook time - so the times can be seen applied proportionally.
However, most foods have an ideal window of a few hours, and meat will evenetually get overly mushy and even dry. As a rule of thumb, for any temperature over 130 F, feel free to push the limit on cooking times and see what you feel comfortable with. If you are cooking a burger or fish at a temperature below 130 F, make sure you stay under 4 hours.
While the ice bath is a necessary part of storing foods cooked sous vide, do not let it intimidate you. Provided you have non-Ziploc bags ice ready, it is as simple as filling a container with roughly an equal ratio of ice to cold water. In the same way that sous vide uses water as an effective way to transfer, an ice bath quickly make sures that the core temperature of food is cold enough to prevent bacteria from growing. Simply putting away food in the fridge is not enough, as the center of a hot steak will stay warm for a lot longer than you think.
The good news is that if food is properly chilled, cooked food can be frozen up to a year. But while ziploc bags are great for sous vide, they are not ideal for long term chilled storage. Over a long period of time, Ziploc bags will allow trace amounts of air into the bag that can create some degradation in the flavor.
Out of the bag, sous vide cooked food is not the most visually appealing. By searing your food, you are not only making it more better to look at, but you are also adding flavor through the Malliard reaction. If you do not already have one, it's highly recommended that you buy a cast iron pan. They are cheap, basically non-stick, and maintain heat extremely well.
As one can imagine, searing is a lot simpler when your food is already fully cooked. You can refer to the time and temperature pages for ingredient-specific guidelines, but the general process looks something like this:
Heat pan on relatively high heat
Dry your food thoroughly and season if desired
Add oil to the pan and wait until it is shimmering or smoking
Sear on each side of your food for about one minute
The last unofficial steps of the process is that you will probably make a mess of your kitchen and occasionally burn yourself. Luckily, there are steps you can take to make these problems less of an issue. A splatter guard is a lifesaver for those who would sear food often. For added convenience, pick one that is dishwasher safe. Also, use an oil with a high smoke point such as grapeseed or sunflower to minimize splashing.
For those who are super serious about the perfect sear for meats with skin such as pork belly or chicken thighs, you can chill your food and flatten it between two weighed-down cookie sheets. This will chill your food so it will not overcook during a longer sear, but also flatten the skin to create an even and perfectly crisped surface.
For reheating something you chilled in your refridgerator, plan on cooking it at its original desired temperature for 45 minutes. If your food is frozen, add 30 minutes.
Reheating is especially useful when planning ambitious meals with foods that require different cooking temperatures. You can reheat the higher temperature foods first and then lower the cooking temperature, before adding lower temperature food.