“As oil is heated, it breaks down, leading to flavor degradation and the release of toxic chemicals. Food is also more likely to stick to a cold pan – another reason to preheat. But exceptions to the preheating rule exist: butter and garlic. Both will burn if the pan is too hot, so you must heat them gently. In all other cooking, preheat the pan and then add the fat, letting it too heat up before adding any other ingredients.”
