TRUTH OR MYTH: Have all of your ingredients prepared and your cooking oil heated before starting to cook.

So many dishes around the world begin by cooking some combination of aromatics (garlic, ginger, chiles, lemon grass) and vegetables (onions, celery, carrots) in hot fat, whether as a sofrito, a mirepoix, a recaito or a ginisa. And most published recipes — including many at New York Times Cooking — instruct you to prepare all of the ingredients separately, heat the oil (or butter or lard) until “shimmering” (or the like) and then begin to cook.

But years ago, I started to rush the process by adding ingredients directly from the cutting board to the pan with the oil. Now I set the pan over low heat and warm the ingredients as I work, stirring in each new ingredient as it’s ready. The heat goes up only once everything is minced, chopped, diced and coated evenly with oil.

This may not be exactly a eureka moment for most cooks, but it goes against the instructions in nearly every published recipe. The myth that all of the ingredients need to be prepared before any cooking starts comes to us from restaurant kitchens, where the concept of “mise en place,” French for put in place, is fundamental.

From outdoor stalls to high-end kitchens, professional cooks start with prepped ingredients and cook them to order, with attention focused on that one skillet (or wok or tadka) at a time. For stir-frying, where the cook is constantly moving the food around in the pan, this works great. And when deep-frying or pan-frying, starting with an empty pan and super-hot oil is integral to the cooking process.

But for slower food, like soups and stews, it’s perfectly fine to start the pan over low heat, and turn the heat to high only once everything is in. Diced vegetables like onions and celery take longer to cook than minced aromatics like ginger and garlic, so put the vegetables in first. They will soften, and then turn golden, and then — quite a lot later — caramelize. (Speaking of: Another persistent myth in American cooking is that it takes 8 to 10 minutes to caramelize onions, which is pretty much impossible unless you are a restaurant chef and stirring onions over high heat is your only job.)

VERDICT: False. When cooking something in a flash, preheated oil and prepped ingredients are necessities. But for other recipes, low and slow is a great start.