Roasting
Roasting is cooking food uncovered in the dry heat of an oven, usually at 200–230 °C / 400–450 °F for vegetables and smaller cuts. The hot air dries the surface so it can brown and crisp, while the inside cooks through more slowly and stays tender and juicy.
How roasting works
An oven heats food three ways at once: hot air moving around it (convection), infrared energy from the walls and elements (radiation) and direct contact with the hot pan (conduction). The pan side usually browns first for that reason.
Browning can't start until the surface dries. While water is still evaporating, the surface stays stuck near 100 °C / 212 °F. Once it dries, it climbs past roughly 140 °C / 285 °F, where the Maillard reaction speeds up and builds savoury, roasted flavour. Above about 160 °C / 320 °F, natural sugars in carrots, onions and squash begin to caramelize, adding sweetness and deep colour.
That is why the oven has to be hot. At 175 °C / 350 °F, vegetables can soften all the way through before their surfaces ever dry out, so they turn tender but pale.
Roasting temperatures
| Food | Oven temperature | Notes |
|---|---|---|
| Most vegetables | 200–230 °C / 400–450 °F | 20–45 min depending on size |
| Whole chicken | 200–220 °C / 400–425 °F | Done at 74 °C / 165 °F in the thigh |
| Pork tenderloin | 220 °C / 425 °F | 71 °C / 160 °F (Health Canada) or 63 °C / 145 °F + 3-min rest (USDA) |
| Large beef or pork roast | 120–165 °C / 250–325 °F | Even doneness; brown at the start or end |
| Tomatoes (slow-roasted) | 120–150 °C / 250–300 °F | 2–3 hours to concentrate |
Space is the secret
Every piece of food gives off steam as it heats. Spread out, that moisture escapes into the oven. Crowded together, it gets trapped between the pieces and they steam instead of roast. Leave a gap about the width of a finger between pieces and use two sheet pans if needed.
Rimmed metal sheet pans beat glass or ceramic dishes for browning because metal transfers heat faster. Tall-sided roasting pans also trap steam around vegetables, so save them for large roasts that need to catch drippings.
Getting the details right
- Cut evenly. Same-sized pieces finish together. Large, dense pieces need longer than small, watery ones.
- Dry the surface. Pat washed vegetables and meat dry. Water on the surface is water the oven has to boil off first.
- Use enough fat. About 1 tablespoon (15 ml) of oil per 450 g (1 lb) of vegetables coats evenly and conducts heat into every nook.
- Salt early. Salting meat hours ahead (a dry brine) seasons deeper and dries the skin for crispness.
- Account for carryover. Large roasts keep rising 3–8 °C (5–15 °F) after leaving the oven. See carryover cooking and resting meat.
Roasting vs baking
Physically they're the same dry-heat process. The words are tradition: we roast meat and vegetables, and bake breads, cakes and casseroles. Roasting usually implies higher heat and the goal of a browned exterior. For intense heat from above only, see broiling.
Questions
Should I roast meat low and slow or hot and fast?
Small, tender pieces like a whole chicken or pork tenderloin do best hot, around 200–230 °C / 400–450 °F. Large roasts cook more evenly at 120–165 °C / 250–325 °F, then get a short blast of high heat or a sear for crust.
Should I use convection for roasting?
Yes, for most roasting. The fan strips away the cool, moist air around the food, so it browns faster and more evenly. Lower the temperature by about 15 °C / 25 °F or check 10–15 minutes early.
Do I need to flip roasted vegetables?
Flipping once halfway gives two browned sides, but the side touching the hot pan browns most. Many cooks skip flipping and simply lay cut faces down for maximum colour.
Do I need to preheat the sheet pan?
It helps with dense vegetables like potatoes and Brussels sprouts. A pan heated in the oven for 10 minutes starts searing on contact, so the bottoms brown before the insides go soft.