Roast Potatoes
Cooking Skills: Potatoes 1
Chapter 3 · Roast Potatoes
Skill goal
Roast potatoes with a crisp golden shell and a fluffy middle.
Shopping list for this chapter
The basics
A good roast potato has a crisp, golden shell and a fluffy middle. Four things make that happen: the right potato (floury), a par-boil that roughs up the surface, very hot fat, and enough space on the tray.
| Step | What it does |
|---|---|
| Floury potato | Breaks down at the edges when par-boiled, making a fluffy layer that crisps |
| Par-boil | Softens the outside and gelatinises the starch |
| Steam-dry and shake | Removes moisture and roughs up the surface |
| Very hot fat | Seals the surface and starts the crisping at once |
| Space on the tray | Crowded potatoes steam instead of roasting |
| Turn only when needed | A crust forms when left alone; turning too early tears it |
- The oil should shimmer before the potatoes go in.
- One layer, with gaps. Use two trays if you need to.
- Pat dry. Wet potatoes spit and steam.
Try it
Level 1 · Start here
Simple roast potatoes (no par-boil)
Raw potatoes straight into hot oil. They are crisp outside and firm inside, but denser than the par-boiled kind in the next recipe.
Ingredients (2 portions)
- 400 g floury or all-rounder potatoes, peeled and cut into 5 cm chunks
- 3 tbsp sunflower or vegetable oil
- 1 pinch flaky salt
- Heat the oven to 200°C fan (220°C conventional, gas 7). Put a roasting tray with the oil in the oven for 10 minutes to get very hot.
- Pat the potatoes dry. Carefully add them to the hot tray (they should sizzle), turn once to coat, and roast for 25 minutes.
- Turn them, and roast for another 20 to 25 minutes, until golden and crisp, and a knife slides in easily.
- Sprinkle with the salt and serve at once.
Hot fat
A tray of hot oil can spit. Use oven gloves, add the potatoes away from your face, and never move a tray of hot fat while the oil is still very hot if you can avoid it.
Level 2 · The classic
Par-boiled, shaken roast potatoes
Par-boiling softens the outside, and shaking roughs up the surface into a fluffy layer. That rough layer is what crisps in the oil.
Ingredients (3 portions)
- 600 g floury potatoes (Maris Piper), peeled and cut into 5 cm chunks
- 1 tsp salt, for the water
- 4 tbsp sunflower or vegetable oil
- 1 tbsp plain flour or fine semolina (optional)
- 1 pinch flaky salt
- Heat the oven to 200°C fan (220°C conventional, gas 7) with the oil in a roasting tray inside.
- Cover the potatoes with cold salted water, bring to the boil and simmer for 8 to 10 minutes, until the outsides are soft but the centres are still firm.
- Drain well, return to the dry pan, and leave to steam for 2 minutes. Put the lid on and shake the pan firmly a few times, until the edges are rough and fluffy. Sprinkle over the flour or semolina if you like and shake again.
- Add the potatoes carefully to the hot oil, turn to coat, and roast for 30 minutes. Turn them and roast for 15 to 20 minutes more, until golden and crisp.
- Season with flaky salt.
Go for gold
Golden yellow-brown is the target, not dark brown. See the food safety box below.
Level 2 · Fragrant
Herb and garlic roast potatoes
The same method, with garlic and herbs added part-way through. If they go in at the start, they burn and turn bitter.
Ingredients (3 portions)
- 600 g floury potatoes, peeled and cut into 5 cm chunks
- 1 tsp salt, for the water
- 4 tbsp sunflower or olive oil
- 1 head head of garlic, broken into unpeeled cloves
- 4 sprigs of rosemary or thyme
- 1 pinch flaky salt
- Par-boil, steam-dry and shake the potatoes as in the previous recipe, and put them into the hot oil.
- Roast for 30 minutes. Turn the potatoes, then add the garlic cloves and herbs to the tray.
- Roast for another 15 to 20 minutes, until golden and crisp. Squeeze the soft garlic out of its skins over the potatoes.
Level 1 · Lighter
Lighter olive oil roast potatoes
No par-boil, much less oil, and the skins left on. These are not as fluffy as a classic roastie, but they are quick and still crisp at the edges.
Ingredients (2 portions)
- 500 g waxy or all-rounder potatoes, unpeeled and halved or quartered
- 2 tbsp olive oil
- 1 tsp smoked paprika or dried oregano
- 1 pinch salt and pepper
- 1 lemon, juice only
- Heat the oven to 200°C fan (220°C conventional, gas 7) with a roasting tray inside.
- Toss the potatoes with the oil, spice and seasoning in a bowl.
- Spread them on the hot tray in a single layer, cut side down, and roast for 35 to 40 minutes, turning once, until golden.
- Squeeze over the lemon juice just before serving.
Experiments
Experiment
Par-boil time
How long is long enough?
- Par-boil three batches of floury potatoes for 5, 10 and 15 minutes. Steam-dry, shake and roast all three together.
- Compare crispness, fluffiness and any that have collapsed.
Look for: Five minutes gives a thin crust and a dense middle. Ten is the sweet spot. Fifteen can collapse and soak up fat.
Experiment
Which fat
Oil, butter or a mix?
- Roast separate trays in sunflower oil, in olive oil, and in a mix of oil with a knob of butter added half-way through.
- Taste each plain.
Look for: Neutral oil gives the crispest result; olive oil has a stronger taste, butter browns quickly and can burn if added early. Goose or duck fat, if you use it, gives a rich taste.
Experiment
Hot tray or cold tray
Does preheating matter?
- Roast two batches, one added to a preheated tray of oil and one added to cold oil on a cold tray.
- Compare the underside.
Look for: The cold-start potatoes are greasier and have a pale, soggy base; the hot ones sizzle and crisp.
Experiment
Shaken or smooth
Is the shaking worth it?
- After par-boiling, shake half the potatoes in the pan to rough them up and leave the other half smooth.
- Roast both.
Look for: The shaken ones have a craggy, extra-crisp crust. The smooth ones are paler and less crunchy.
Experiment
Temperature
Hotter or slower?
- Roast one batch at 180°C fan and another at 210°C fan, adjusting the time until each is golden.
Look for: The lower oven takes longer and gives a paler potato; the hotter one gets crisp quickly but can go dark before the middle is done.
Tasting notes
| What I tried | Method or amount | What I saw | What I thought | Will I do it again? |
|---|---|---|---|---|
| Simple roast | ||||
| Par-boiled roast | ||||
| Herb and garlic roast | ||||
| Lighter olive oil roast | ||||
| Par-boil 5, 10 and 15 min | ||||
| Oil, butter or mix | ||||
| Hot vs cold tray | ||||
| Shaken vs smooth | ||||
| 180 vs 210°C |
Troubleshooting
| Problem | Likely cause | What to do |
|---|---|---|
| Pale and soggy | Fat not hot, tray crowded, or wet potatoes | Preheat the tray; use space; dry the potatoes |
| Hard in the middle | Too big, or par-boil too short | Cut smaller or par-boil a little longer |
| Collapsed or greasy | Par-boiled too long, or floury and old | Par-boil for 8 to 10 minutes |
| Stuck to the tray | Turned too early | Leave for 20 to 25 minutes before turning |
| Dark and bitter | Too hot, or garlic added early | Aim for golden; add garlic late |
| Not crisp the next day | Normal: roasties soften as they cool | Re-crisp in a hot oven for 10 minutes |
Food safety: hot fat and acrylamide
Go for gold. When starchy foods such as potatoes are fried, roasted or baked at high temperatures they form a chemical called acrylamide, which the Food Standards Agency says could raise cancer risk. Its advice is to cook to a golden yellow, not dark brown, and to follow the packet instructions on bought chips and roasties. A balanced diet matters more than any single food, so this is a nudge about colour, not a reason to avoid potatoes.Hot fat is a burn and fire risk. Use oven gloves, keep children away from the oven, and never put water on a fat fire. Raw potatoes: keep them somewhere cool, dark and dry (above about 6°C), not in the fridge and not in the light. The Food Standards Agency advises against keeping raw potatoes in the fridge if you will roast or fry them, because the cold raises the amount of acrylamide that forms when they brown. Light turns the skin green and makes sprouts, and the green and the sprouts contain a natural toxin (solanine) that is bitter and can upset your stomach. Cut away sprouts and any green patches generously; if a potato is green all over, or tastes bitter, throw it away. Cooking does not remove it.
Cooked potatoes: cool them quickly (spread out, within 1 to 2 hours), keep them covered in the fridge, and eat them within 2 days. Reheat until steaming hot all the way through, and only once. (This is the general chilled-leftovers advice relayed by local-authority food-safety pages; unlike rice, potatoes have no special rule of their own, but they are starchy, so they are treated with the same care.)
Checkpoint: can you do this now?
- I can pick a floury potato for roasting.
- I can par-boil, steam-dry and shake potatoes.
- I know why the fat needs to be very hot.
- I can roast to golden, not dark brown.
- I can make roast potatoes without par-boiling.
Next chapter
Cooking Skills: Potatoes 1, chapter 4 is Chips, Wedges and Fries: cutting evenly and cooking twice.