Soggy roast vegetables

A crowded tray is a steamer

Vegetables release a great deal of water as they heat. On a tray with space between the pieces that water evaporates, the surfaces dry, and they brown.

Piled or touching, the water cannot escape. It collects between the pieces, the air immediately around them becomes saturated, and every surface stays at boiling point. The result is exactly what a steamer produces, because it is exactly what a steamer is.

Two trays with space beat one crowded tray every time, even though it feels like more work and more washing up.

What is causing it

• Too much on the tray. The commonest cause by a long way. Vegetables should be in one layer with visible gaps between them.
• Too small a tray, or a deep-sided roasting tin that traps steam around the food.
• The oven not hot enough. Roasting vegetables wants a genuinely hot oven, not a moderate one.
• Not preheating the tray. A cold tray means the undersides sit and sweat before they start to colour.
• Too little fat. Fat conducts heat to the surface and speeds drying. A mean drizzle gives pale vegetables.
• Wet vegetables. Washed and not dried, or thawed from frozen, both flood the tray.
• Cut too small, which increases the total surface releasing water.
• Covered with foil, which is a braise however hot the oven is.

Getting them browned

1. Cut the vegetables into reasonably large, even pieces — chunks rather than dice.
2. Dry them if they have been washed. This matters more than it sounds.
3. Preheat the oven properly hot, and preheat the tray with the fat in it.
4. Toss the vegetables in enough oil or fat to coat them fully, and season.
5. Spread them in a single layer with space between them. If they touch, use a second tray.
6. Roast without stirring for the first twenty minutes so the undersides can colour, then turn them once.
7. If the tray has flooded, tip the liquid off, spread them out further and turn the oven up. They will still brown.

By vegetable

Potatoes

Parboil first, rough up the edges, and roast in genuinely hot fat. The best browning of any vegetable.

Root vegetables

Carrot, parsnip, beetroot, celeriac. Dense and low in water; the most forgiving.

Brassicas

Broccoli, cauliflower, sprouts. Brown well and burn quickly at the edges. Hot and fast.

Courgette and aubergine

Very wet. Salt and drain first, or roast them alone with plenty of space.

Mushrooms and tomatoes

The wettest. Give them their own tray or accept that they will steam whatever is beside them.

Mixing them

A tray of everything cooks nothing well. Group by density and water content.

Common questions