Roasting is dry-heat cooking where hot air surrounds food and heat transfers through convection and radiation. It allows surface temperatures above 150°C, triggering extensive Maillard browning across every exposed surface while the interior cooks more gently through conducted heat. The fundamental challenge of roasting — and the measure of a cook's skill — is managing the gradient: achieving a deeply browned, crisp exterior and a juicy, evenly cooked interior at the same time. The outside wants high heat. The inside wants low heat. Every roasting technique ever invented is an attempt to solve this paradox.
Quality hierarchy: 1) Dry surfaces — moisture is the enemy of browning in the oven just as it is in the pan. Pat meat dry. Oil vegetables. Uncovered, never wrapped (wrapping creates steam, which is braising). A chicken dried with paper towel and left uncovered in the fridge overnight develops skin that crisps in the oven. A chicken straight from its packaging, wet with purge, develops skin that steams and stays flabby. This is NON-NEGOTIABLE. 2) Space — every piece of food needs air circulation on all sides. Overcrowding a sheet pan means the vegetables touching each other steam in their shared moisture instead of roasting in hot air. A single layer with 2cm gaps between pieces. If it doesn't fit on one pan, use two pans. 3) Heat for size — small items (vegetables, chicken pieces, fish fillets) roast at 220–260°C: high heat, fast cook, maximum browning before the interior overcooks. Large items (whole chicken, pork shoulder, prime rib) roast at 150–175°C: low heat, slow cook, even interior before the exterior burns. 4) Elevation — a wire rack over the roasting pan lifts the food off the surface. The bottom gets hot air instead of sitting in its own rendered fat and juice. Without a rack, the bottom braises while the top roasts — two different textures, uneven cooking. For a whole chicken: rack is NON-NEGOTIABLE. For roast vegetables: spread on a sheet pan in a single layer, no rack needed. 5) The thermometer — internal temperature is the only reliable indicator of doneness. Colour, timing, and the 'poke test' are approximations. A probe thermometer reading 62°C in the thickest part of a beef roast means medium-rare. A brown crust that looks perfect means nothing if the interior is 75°C.
The reverse sear for large roasts: start at 120°C until the internal temperature reaches 5°C below your target (this could take 2–3 hours for a prime rib). Remove, rest for 20 minutes. Then blast at 260°C or under the broiler for 8–10 minutes to develop the crust. The result: edge-to-edge even doneness with a mahogany brown crust. No grey band. No overcooked exterior around a raw centre. For roast vegetables: toss with just enough oil to coat (a tablespoon per sheet pan), season with coarse salt, spread in a single layer, and don't touch them for 15 minutes. The caramelisation happens on the contact surface between vegetable and hot pan. Every time you stir, you break the forming crust and reset the browning clock. Stir once, at the halfway mark, then leave them alone. For whole chicken: dry brine (generous salt, uncovered in fridge overnight). Start at 230°C for 20 minutes to crisp the skin while the bird is still cold. Drop to 180°C for the remaining 40–50 minutes. The skin sets crisp during the blast and the lower temperature finishes the interior gently. Thigh should read 74°C. Let it rest 15 minutes. When you carve, the juices should stay in the meat, not flood the board.
Overcrowding — the single most common roasting failure. Twenty Brussels sprouts on a pan that fits twelve means ten of them steam instead of caramelise. The result: pale, soft, slightly bitter instead of deep brown, crispy, sweet. Not preheating the oven — putting food in a cold or warm oven means the first 15 minutes are spent heating up, during which time the surface steams instead of sears. Preheat fully — 20 minutes minimum for most ovens. Opening the oven constantly — every time the door opens, temperature drops 15–25°C and takes 5 minutes to recover. Set a timer, trust it. Same temperature for everything — a 200g chicken breast and a 6kg prime rib cannot roast at the same temperature. Small items high, large items low. Not resting before carving — carryover cooking and juice redistribution are just as critical after roasting as after pan-searing. A whole chicken needs 15 minutes. A prime rib needs 25.