Throwing a handful of hardwood chips into your charcoal kettle can infuse your steak or slow-cooked pork with a richly memorable flavor, but that combination of heat and smoke isn't the only way to prepare smoked foods. Separating the smoke from its heat, and exposing your foods to the smoke alone, results in a very different end result. Cold-smoking is a bit more challenging for the home cook, but well worth the effort.
Hot or Not
Both hot and cold smoking give foods a distinctive and appealing flavor, but they're very different processes. Hot-smoking in a conventional smoker cooks the foods as they smoke, so they become food-safe. However, cooking causes physical changes to the structure of proteins, and alters the texture of the finished food. Cold-smoking doesn't do that, so -- for example -- cold-smoked salmon retains the silky-soft texture and rosy color of the uncooked fish, while hot-smoked salmon becomes firm and pale. You must make cold-smoked meats food-safe either by curing them in salt, as hams and cold-smoked fish are, or by cooking them afterward.
Preparing Your Foods
In most cases, you'll begin by curing or marinating the meats to preserve or flavor them. Meats can be cured either in a dry mixture of salt and other flavorings, or in a brine made by dissolving the same ingredients in water. Foods intended for immediate consumption might only require 20 to 30 minutes of curing or brining, while large cuts destined for long-term preservation may need days. Once the meat is adequately cured, it should be blotted dry and left uncovered overnight in your refrigerator to dry. This forms a tacky surface -- the "pellicle" -- that helps smoke adhere.
Smoking Your Foods
Arrange the meats on flat racks in your smoker, or hang them from racks or hooks as appropriate. The actual combustion takes place outside of your smoke chamber, and the smoke is routed through to flavor your foods. Smoking usually takes place at temperatures ranging from the mid-70s to mid-80s Fahrenheit, and 100 F is the upper limit for cold-smoking. Commercial smokers are often refrigerated, to keep the temperature at a food-safe 40 F or lower. You can achieve the same effect by "hacking" a surplus refrigerator and using it as the smoke chamber. Depending on the size and type of meats you're preparing, they might require as little as an hour or two in the smoker, or as long as a few days.
Once your meats have finished cold-smoking, their paths diverge. For example, cold-smoked fish is usually served as-is, in thin slices. A pork roast or turkey breast might be lightly smoked for flavor, then roasted conventionally in your oven. Home-cured bacon is often cold-smoked first and then hot-smoked afterward, rendering it food-safe. Dry-cured sausages and country hams have the longest road, hanging in a cool and well-ventilated place for weeks or months after smoking. Whichever type of cold-smoked meats you make, pay scrupulous attention to sanitation and food safety. Any cured meat represents a risk of food-borne illness if it isn't handled properly.