More home cooking is spoiled by the wrong heat than by the wrong ingredients. Food comes out grey instead of browned, or burnt outside and raw inside, and the recipe gets blamed. Heat is the one variable people adjust least and it changes the result most.
High heat is for browning, and browning is flavour
When food browns, it is not just colouring: hundreds of new flavour compounds form that did not exist before. That is why a seared piece of meat, a properly roasted vegetable and a browned onion taste of so much more than their boiled equivalents. Browning needs a hot pan, a dry surface and space. Wet food, a crowded pan or a lukewarm one gives you steam instead, and steamed food cannot brown until every drop of water has gone.
Low heat is for anything that needs to become tender
Tough cuts, dried pulses, root vegetables and any pot with liquid in it want a long, low, barely bubbling heat. High heat does not make them tender faster; it makes the outside tighten and the liquid boil away while the inside stays firm. A stew at a rolling boil is a stew being ruined. You want the occasional lazy bubble, and a lid that lets a little steam out.
Most dishes need both, in this order
Brown first on high, then drop the heat and add liquid. That order is the structure of almost every stew, curry, ragù and braise ever made, and doing it in the opposite order is why home versions taste thin. The browned bits stuck to the bottom of the pan are the best part. When the liquid goes in, scrape them up — that is where the depth comes from.
Four signals that tell you the pan is ready
Oil shimmers and moves like water when it is hot enough to brown. If it smokes heavily it has gone too far. Food sizzles immediately when it touches the pan. Silence means the pan is too cool and whatever you added is now absorbing oil rather than browning in it. Food releases itself. Meat and fish stick to a hot pan and then let go once a crust has formed — if it is stuck, it is not ready to turn. And the sound changes. A sizzle that turns to a quiet hiss means the water has gone and the browning has started.
The two most common mistakes
Cooking everything on medium, which browns nothing and tenderises nothing. And putting cold food into a cold pan and turning the heat up under it, which guarantees the food absorbs fat before anything happens. Heat the pan first, then the oil, then the food — in that order, every time.
Hot to brown, low to tenderise, hot first and low second, and listen to the pan. Most of what looks like a skill gap in home cooking is a temperature setting.