Rescues · TO ROAST
Vegetables are soft and pale rather than browned.
Why it happens
Crowded tray. Released moisture cannot escape, so everything steams in it. Two trays, always, rather than one deep pile.
Recovering it
Pale and soft can usually be pushed — spread the food over two trays, raise the heat, and give it another ten minutes. Burnt outside with a raw middle is the hard case: cover with foil and drop the temperature so the interior catches up without the surface going further, and accept the crust is as dark as it will be. Overcooked meat cannot be recovered; slice it thin and serve it with something moist.
The mechanism
Dry air is a poor conductor of heat compared with water or metal, which is why an oven at 200°C does not cook nearly as fast as boiling water at 100°C. That poor conduction is the point: it lets the surface reach browning temperature — above roughly 150°C — while the interior climbs slowly enough to finish at the same time. Two things spoil it. Moisture is the first: any water on the surface, or steam trapped by crowding or a lid, holds the surface at 100°C and it cannot brown until that water has gone. Contact is the second: a hot tray transfers heat far faster than the air does, so the underside browns hardest, and food touching its neighbours has no exposed surface between them and steams in the gap. This is why roasting is the technique most improved by using a bigger tray.
The full TO ROAST lesson — how to tell, where to practise it, what it carries to.