First, select the right pot. Opt for a stainless steel rather than an iron pot because the latter will hasten rancidity. For the same reason, choose a tall and narrow, rather than a squat and wide, pot to minimize surface area. Oxygen is an enemy of oil.

The longer an oil is heated, the more quickly it will decompose. Therefore, do not preheat the oil any longer than is necessary. If you are cooking more than one batch of food, add each new batch without delay (unless time is needed to adjust the cooking temperature). Turn off the heat immediately after removing the last batch from the oil.

(continue here...)