Soggy roast potatoes

The five causes

Work down the list — most failures are the first two.

The potatoes were wet

Surface water has to boil off before anything can crisp, and while it does the surface stays at 100°C. Drain thoroughly and let them steam dry in the colander before they go anywhere near fat.

The tin was crowded

Potatoes release steam. In a crowded tin that steam has nowhere to go and they braise in it. A single layer with space around every piece.

The fat was not hot

Cold fat soaks in rather than searing the surface. Heat the fat in the tin in the oven first, until it shimmers, then add the potatoes.

The surface was smooth

A crisp shell needs a rough, starchy exterior. That is what parboiling and shaking creates, and skipping the shake is the commonest omission.

The wrong potato

A waxy potato does not go fluffy and cannot form the crust. Use a floury variety — Maris Piper, King Edward, Russet.

The method that works

1. Peel floury potatoes and cut into large, uneven chunks. Corners and edges are where the crisp happens.
2. Boil in well-salted water until the outsides are genuinely soft — slightly overdone is better than under.
3. Drain and leave in the colander for two or three minutes to steam dry.
4. Put the lid on the pan or the colander and shake hard until the outsides are fluffy and roughed up.
5. Meanwhile, heat plenty of fat in a roasting tin in a hot oven — around 200 to 220°C — until it is properly hot.
6. Add the potatoes carefully in a single layer, turning them to coat, and return to the oven.
7. Turn once after about half the time. Do not fuss with them beyond that.
8. Season with salt when they come out, and add garlic or herbs only in the last ten minutes, or they burn.

Rescuing a tray in progress

• If they are pale and soft, turn the oven up, spread them into a single layer across two tins, and give them longer.
• If they are greasy, the fat was not hot enough. Drain the tin, turn the oven up, and continue — some of it will crisp off.
• If they are dark but soft, they were crowded. Split them across two tins and finish them.
• If they are leathery, they were cut too small or roasted too long at too low a temperature. Nothing to be done this time.
• A grill for two or three minutes at the end rescues more trays than anything else. Watch it constantly.

Improvements worth making

• Add a little bicarbonate of soda to the boiling water. It breaks down the surface further and gives a rougher, crisper exterior. A quarter-teaspoon is plenty.
• Use beef dripping, goose fat or a neutral oil with a high smoke point. Olive oil is fine but its flavour is largely destroyed at roasting heat.
• Parboil in advance. Boiled, shaken and cooled potatoes roast perfectly from cold and can sit in the fridge for a day.
• Do not cover them. A lid or foil traps steam and guarantees softness.
• Semolina or flour instead of a shake works — a light dusting on the roughed-up surface gives an even crisper shell.

Common questions