Why are my roast potatoes not crispy?
The parboil, the roughing up and the properly hot fat — the three steps that separate crisp roast potatoes from disappointing ones.
- Difficulty
- beginner
- Time
- 1 hr 10 min
- Read
- 2 min
Short answer
Parboil them, drain and shake them hard to roughen the surfaces, then get them into fat that is already smoking hot. Crowding the tin and skipping the parboil are the two things that guarantee soft potatoes.
A crisp roast potato is a rough, starchy surface that has been fried by hot fat. Everything below either creates that surface or makes sure the fat is hot enough to crisp it rather than soak into it.
What you'll need
- Floury potatoes
- Roasting tin
- Fat with a high smoke point
- Salt
Step by step
- Use a floury variety.Maris Piper, King Edward, Rooster. Waxy salad potatoes will not go fluffy inside or rough outside — the variety genuinely matters here.
- Cut them into even, fairly large pieces.Halves or thirds. Small pieces are all crust and no interior; uneven ones cook at different rates.
- Parboil for 8-10 minutes in salted water.Until the outsides are just starting to soften. This is what creates the surface that can be roughened.
- Drain thoroughly and let them steam dry.Leave them in the colander for a couple of minutes. Surface water is the enemy of crisping.
- Shake them hard in the pan.Lid on, shake firmly until the edges look ragged. That rough starchy surface is what turns into crust — the single most important step.
- Heat the fat until it is shimmering hot first.Put the tin with the fat in the oven while the potatoes parboil. Cold fat soaks in; hot fat fries. This is not optional.
- Add them carefully and turn to coat.They should sizzle loudly the moment they land. If they do not, the fat was not hot enough.
- Give them space and turn them once.A crowded tin traps steam and everything goes soft. Use two tins if you need to. Turn once, around halfway.
Tips
- A dusting of semolina or flour after shaking gives an even crisper crust. Not traditional, but it works.
- Beef dripping and goose fat crisp better than oil because of their higher smoke point. Rapeseed or sunflower oil works well if you want a vegetarian version.
- Do not cover them or hold them in a warm covered oven. They soften within twenty minutes. Time them to come out last.
Common mistakes
- Putting potatoes into cold fat — They absorb it instead of frying in it, and end up greasy and soft rather than crisp.
- Crowding the tin — Steam cannot escape, so the potatoes effectively braise. Use two tins rather than one full one.
Questions people ask
Do I have to parboil roast potatoes?
For genuinely crisp ones, yes. The parboil creates the soft starchy surface that the shaking roughens up, and that rough surface is what crisps.
Can I prepare roast potatoes in advance?
Yes — parboil, shake and cool them, then keep them in the fridge for a day. They roast straight from cold and it removes a job from the day.