For hundreds of thousands of years, fire provided our only means of cooking food. Today, a plethora of technology gives us other options in the kitchen—but that primal flame remains an important part of what it means to cook. In his new book, Finding Fire: Cooking at its Most Elemental, Sydney-based Chef Lennox Hastie shares recipes and techniques that celebrate cooking with flames. Below, we've excerpted his expert guidance on on the six stages of fire, from spark to cold cinders.
Ignition is the first stage of lighting a fire, the spark that causes combustion. It may seem absurd, but the temperature of the actual fuel affects your ability not only to light a fire but to maintain one, which is why heat is fundamental to fire production.
Every fire starts with the ignition, which can be caused by a match, friction, lightning, or focused light. Keep your ignition as natural as possible. Don’t use treated woods as they may taint ingredients or impart toxic chemicals. Be mindful of some commercial fire starters as they may rely on highly flammable fuel to help generate flames.
The smoking stage occurs immediately after the wood is lit and heated, leading to evaporation of water and the release of carbon dioxide. The wood will produce white smoke until it heats sufficiently for full combustion.
Next is the actual fire, or flames. The fuel is burning away, flames are rising and things are heating up, creating volatile gases. There is a tipping point in this process when the heat is on the incline, known as a flashover. The released gases are ignited in an exothermic reaction producing an intense heat.
Make sure all your fire is well stacked before this, as adding wood at this stage will reduce the temperature. In reality, many of the stages of wood combustion occur simultaneously; wood gases can be flaming and the edges of the wood can be glowing red as the embers burn, while water in the core of the piece is still evaporating.
You can cook with flames so long as they are indirect or offset; the flames should not be in direct contact with the ingredient.
During this phase, ‘blue’ smoke (in contrast to the billowing white smoke from the previous stage) is produced, which is ideal for smoking ingredients. You can suspend food about the fire for direct smoking (hot smoking) or siphon the smoke into a separate chamber for cold smoking.
As certain compounds of the wood are burnt off, the flames die down, the heat rises, and embers emerge.
Embers are glowing wood. By now the only remaining fuels in the wood are carbon and sugar chains of cellulose, hemicellulose, and lignin.
When cooking directly, there should not be any fire from the embers themselves. Most people make the mistake of grilling over actual flames. However, it is the embers that provide the most intense, consistent, and clean heat. Flames are still burning those volatile gases, which can potentially taint the food. When you cook over embers, the natural fats, oils, and juices from ingredients dripping onto them can create a flame, but this should not be confused with a burning wood fire. This is the ideal time to cook.
Depending on the wood type, the embers tend to break down into even pieces and can be fragile, shattering like glass. The temperature of embers will eventually plateau. You can cook on the rise, but it is this plateau period that offers the most consistent heat and optimum time to cook.
It is fine to add more wood as you are cooking, but you need to be mindful that you will need time to let the flames subside, and allow the heat to rise again.
Once the embers have plateaued, the embers experience decay and their temperature begins to decline. This is an ideal point for cooking sides of fish where the majority of the cooking can be done over intense embers on the skin side and then turned to complete cooking the flesh side over a gentler heat.
The embers are now covered in a fine ash and almost appear dormant but under the surface they remain a powerhouse of heat. It is not until you put your hand over them that you realize how much heat is still being generated.
Ash is the embers that have broken down completely. The whitish ash is made up of compounds of potassium and calcium, and has a beautiful residual warmth. A fine dusting provides an even heat ideal for slowly cooking ingredients like onions, potatoes, and eggs.
Extinguished combustible wood that ceases to burn, cinders are the cold remains of the fire. While cinders can’t be cooked with, they can be used as a base for lighting your next fire.
Do you cook with an open flame? What's your favorite dish to serve?