熟物之法，最重火候。有須武火者，煎炒是也；火弱則物疲矣。有須文火者，煨煮是也；火猛則物枯矣。有先用武火而後用文火者，收湯之物是也；性急則皮焦而裡 不熟矣。有愈煮愈嫩者，腰子、雞蛋之類是也。有略煮即不嫩者，鮮魚、蚶蛤之類是也。肉起遲則紅色變黑，魚起遲則活肉變死。屢開鍋蓋，則多沫而少香。火熄再 燒，則走油而味失。道人以丹成九轉為仙，儒家以無過、不及為中。司廚者，能知火候而謹伺之，則幾於道矣。魚臨食時，色白如玉，凝而不散者，活肉也；色白如 粉，不相膠粘者，死肉也。明明鮮魚，而使之不鮮，可恨已極
List of Essential Knowledge::Heat control
In the art of cooking, the most important skill is one’s ability in controlling heat . Some ingredients require a strong flame, such as those being pan-fried or stir-fried. If a weak flame is used on such ingredients, they will become wilted and lifeless. Some ingredients require a gentle flame, such as those for stewing. Using an aggressive flame will make such ingredients tough and dry. Others ingredients require one to begin cooking with a strong flame but finish with a gentle flame, such as those dishes with ingredients requiring sauce reductions. If one is impatient during the reduction process and uses heat that is too strong, the ingredient’s surface will be charred while the inside remains raw. Certain ingredients become tender with prolonged cooking, such as kidneys and (chicken) eggs, however some ingredients such as fresh fish and clams, will not become tender if it is even exposed to a slightly stronger flame. When one does not remove meat from the heat in a timely manner after its completion, its colour will not be an appetizing red but rather a charred black. Likewise, a fish not removed from the heat in a timely manner will not be tender and “alive”, but rather dry and “dead”. If you frequently open the pot’s lid while the food is cooking it will tend have foamy sauces and be less fragrant. As well, if you attempt to relight a spent flame while cooking, the ingredients will be rendered of its oil  and become flavourless.
The Daoists attain perfection of sainthood by channeling their internal forces through “nine revolutions”  and the Confucianists attain perfection by not faulting and striving to overcome failure . Likewise, if a cook knows how to control the cooking flame and attends to it diligently and attentively, they too are close to attaining perfection. When eating fish, if the flesh is as translucent white as jade and holds together without flaking apart, this is tender and “live” flesh. But if the flesh is white, opaque like powder, and falls apart, this is “dead” flesh. To have a fresh fish and then cook it until it is stale and flavourless is something truly despicable.
: Huo hou (火候) lacks a good direct translation. It describes the processing of controlling both (1) the intensity of the cooking heat and (2) the length of time the that the food stays in contact with the heat, with the latter being key in a traditional pit or charcoal stove. I previously wanted to say “flame control”, since Chinese cooking without a real flame is slightly impaired IMHO, even with new induction technologies, but “heat control” sounds more right.
: Not sure how to phrase it, but the idea is that if you’re cooking on a twig or straw fired flame and it goes out while your meat is still being cooked, then consider it lost. Restarting the flame would produce low heat, causing the meat to stew and render its fat, thus producing something less than perfect.
: Dan (丹) is this Daoist concept that can be either interpreted as being a pill-formed panacea-like medicine (仙丹) or as the fluid/elixir manifestion of qi-like forces (丹氣) in one’s body (See Dantian). The “nine-revolutions” (九轉) is a Daoist concept on the tiers of transformation needed to imbue body or substance with mystical powers. I think in the acheiving perfection context in this part of the text, saying something like “channeling of internal forces to attain sainthood” works much better than saying “brewing mystic medicines to achieve powers”. As such, I put down the former as translation.
: The concepts of Wuguo (無過), not commiting errors, and Buji (不及), believing in inadaquacy, are important guides to conduct of a Junzi (“a perfect man” or what I translate as “true gentlemen”). The former concept is well summed up in the Chunqiu Zuozhuan (春秋左傳::宣公二年), which quotes “Who amoung us have not erred? To err and be able to correct oneself, there is nothing better than this.” (人誰無過，過而能改，善莫大焉) The latter is well understood through a quote from Confucius: “Study diligently as if you’re about fail and as if you’re about to be surpassed.” (子曰：學如不及，猶恐失之) Basically the ideas sum up as: “Do not do bad things and work very hard”.