It’s the culinary equivalent of the chicken or the egg question. When adding oil to a skillet, Rob Sapp, of Ann Arbor, Michigan, wants to know whether the dry pan should be heated first or if the oil should go into the cool pan and heat simultaneously?

At Milk Street, we almost always add oil to a cold pan, then heat the two together. This method allows the oil to act as a visual indicator of how hot the pan is: As it heats, the oil ripples, shimmers and eventually barely smokes. Conversely, heating a dry pan offers no visual cues, which risks overheating. Adding oil to an overheated pan can cause splattering—and potentially even a grease fire.

When using carbon-steel and cast-iron pans, some people like to heat the dry pan first, then add the oil. This is because high heat causes the oil to oxidize and polymerize, allowing it to bond to the metal, filling in any small pits and divots—a process that seasons the pan, essentially giving it a nonstick surface. But in our testing we found we could season a carbon-steel pan just as easily by starting with oil in a cold pan, then heating it until smoking, and repeating the process until the pan develops a golden-brown patina. (This requires high heat; we found that heating the pan and oil over medium produces a sticky residue instead of the near-nonstick coating we desired.)

The other part of the equation is when to add the food. Most foods should be added once the oil is hot, which ensures better searing and browning. But when cooking delicate ingredients—such as fresh herbs and spices—or when sweating aromatics like onions or garlic, the ingredients should go in the pan with the cool oil to slowly draw out their flavor without risk of burning.

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