Can I par-boil roast potatoes the day before?

This is the single most useful prep-ahead job in a roast dinner, because par-boiled potatoes actually improve with a rest: the surface dries out further in the fridge, which means less water to drive off in the oven and a better crust.

Step by step

1. Choose a floury variety and cut for the tray.Maris Piper, King Edward or Rooster. Cut to roughly even pieces around 5 cm; halves for small potatoes, quarters for large. Uniformity matters more than any particular size.
2. Par-boil from cold, salted, to the edge of collapse.Cold water, about 10 g salt per litre, bring to the boil then simmer for 8–10 minutes. You want a skewer to meet slight resistance at the centre and the outer surface to be visibly soft and starting to break. That fluffy outer layer is the entire point.
3. Drain and steam dry properly.Drain in a colander, then return to the hot empty pan off the heat for 2–3 minutes with the lid off. The residual heat drives moisture off as visible steam. Do not skip this.
4. Rough up while hot.Put the lid on and shake the pan hard two or three times, or run a fork over each piece. You are making a fuzzy starchy exterior with a lot of surface area. Overdo it and they will crumble; underdo it and you have smooth potatoes that fry rather than crisp.
5. Cool on a tray in a single layer, uncovered.Spread them out so they cool fast and the surface dries in the air. Leave them uncovered for the first half-hour at least. When completely cold, cover loosely and refrigerate for up to two days.
6. Roast straight from the fridge into properly hot fat.Get the fat smoking-hot in the tray in a 200–220°C oven before the potatoes go anywhere near it. Cold potatoes into hot fat is fine and is what you want; cold potatoes into a cold tray is how you get soggy ones. Allow perhaps five extra minutes over the usual time.
7. Or freeze them at the cooled stage.Open-freeze on the tray until solid, then bag. Roast from frozen in hot fat, allowing roughly ten minutes more. This is how the frozen roast potatoes you buy are made and it works just as well at home.

Tips

• A tablespoon of semolina or fine polenta tossed through the roughed-up potatoes before they go in the fat gives a noticeably crunchier shell.
• If the fridge is full, par-boiled potatoes will sit happily at cool room temperature for a few hours on the day itself — cool them fast and eat them the same day.
• The tray you cool them on can be the tray you roast on, which saves washing up and avoids handling them again once they are fragile.

Common mistakes

• Putting warm par-boiled potatoes into a sealed container — Trapped steam rehydrates the roughed-up surface into paste, and you will not get a crust off it.
• Storing them in water to stop them browning — It undoes the drying completely. Air-cooled and uncovered is right; they will not brown meaningfully once cooked.
• Under-par-boiling to be safe — A firm par-boiled potato has no fluffy exterior, so there is nothing to crisp. Take them right to the edge.

Questions people ask