How heat travels

A cooking method is really just an answer to three questions: which kind of heat, how hot, and how wet? Once you can read a technique that way, you stop memorizing recipes and start predicting what the food will do.

The three routes, in the kitchen

We met conduction, convection and radiation in chapter 1. Here's what each one feels like at the stove, and what it's good at.

Conduction — contact heat

Whatever touches a hot surface heats up fast. This is the searing-hot zone where a steak meets cast iron, where a pancake browns, where an egg sets against the pan. It's the most intense heat you'll use — a skillet can sit at 200 °C+ — but it only reaches what's flat against the metal. That's why you press food down for contact, and why a warped pan cooks unevenly. Metal that conducts well and holds heat (cast iron, carbon steel, thick aluminum) gives steadier, more even browning than thin, flimsy pans.

Convection — heat carried by a fluid

Air, water and oil all carry heat as they move. An oven bathes food in hot air; a pot surrounds it with water; a fryer immerses it in oil. Convection reaches every surface at once, not just the bottom — but each fluid has a very different ceiling:

• Air is a poor conductor, so a 200 °C oven feels gentle — you can reach in for a second. It browns slowly and evenly.
• Water tops out near 100 °C and can't go higher while it's liquid. Gentle, fast at transferring heat, but it can't brown.
• Oil can climb to 180–200 °C, so frying both surrounds food and browns it — the best of both worlds, which is why fried food is so crisp.

Radiation — heat across a gap

A glowing grill, a broiler, the coals of a fire: these throw infrared energy across open space. Radiation browns the facing surface hard and fast without touching it, which is why grill marks are sharp and a broiler can blister the top of a dish in seconds. It falls off quickly with distance, so the rack height under a broiler is a real control.

The great divide: dry heat vs moist heat

The single most useful split in all of cooking is whether water is in the picture. It decides the surface temperature your food can reach — and therefore whether it browns, how fast it cooks, and what texture you get.

Dry-heat methods — searing, roasting, grilling, frying, baking — let the food's surface climb well past the boiling point of water, into the browning range (140 °C+) and beyond. Crust, color, roasted aromas. Moist-heat methods — boiling, steaming, poaching, simmering, braising — surround food with water or steam, which can't exceed ~100 °C. Gentle, even, great for melting tough tissue into tenderness, but pale: no browning is possible while the surface stays wet.

Why this is the foundation

Every choice downstream flows from here. Want a crust? You need a dry, hot surface — so pat the food dry and don't crowd the pan (crowding traps steam and drops you back below the boiling ceiling). Want a tough cut meltingly tender? Moist heat, low and slow, is your friend. Want both crust and tenderness? You'll combine families — sear first, then braise — which is exactly what good cooks do without thinking about it.

Heat is one of your two levers. The other is seasoning — and it starts with salt.