Make your roasties the talk of the Christmas table XANTHE CLAY

Heston’s top chef shares his secrets to help you avoid soggy spuds at your festive feast

The Christmas feast stands or falls on its roast potatoes. If the turkey is a bit dry, you can slosh extra gravy on, and soggy sprouts are the sort of thing generations bond over. But potatoes that are anything other than cracklingly crisp, hot and golden, are a dinner disaster.

Ashley Palmer-watts well understands the power of the roastie. The chef director at London’s two-michelin-star restaurant t Dinner by Heston Blumenthal hal also oversees the kitchen at t Blumenthal’s Michelin-starred starred Hind’s Head in Bray. ray. But Sundays are spent cooking lunch (nine times es out of 10 a roast chicken), for his wife, Emma, and d children, Max, nine, and Sophia, seven – and Palmer-watts er-watts will be at the stove tove on Christmas s Day as well.

Roast potatoes are always front ont and centre. e. “I am the most pedantic person about roast st potatoes. I could talk all day about them,” he admitted to me when I visited the Fat Duck Experimental Kitchen, on an industrial estate near Maidenhead. Heston was not beetling around inside: he was in Provence for research, exploring the minerality of foods. But in the sleek grey and white test kitchen, the three clocks on the back wall showed the times in London, Melbourne and Dubai (there is a Dinner already in Melbourne, while the Dubai outpost is due to open next autumn). And it turns out time – and patience – are key components to the perfect roast spuds, which should have “a perfectly cooked inside and an almost glassy-crisp outside,” explained Palmer-watts. But before all that, the potatoes themselves need to be right. The best this month are Maris Piper, according to Palmer-watts, but that will change through the year, as the level of sugar fluctuates with each variety during storage. Dry matter – the non-water part of the potato – also varies. Too much and the potatoes will fall apart when they are cooked, too little and they will be soggy. I’ve always par-coo par-cooked my potatoes in fast-b fast-boiling water, so that the ed edges are crumbly but the ins inside is underdone. But tha that, Palmer-watts told m me, “is one of the key mista mistakes”. Instead, we need to be b simmering th them gently un until they are cook cooked throug through. “Yo You want to rem remove as muc much water as p possible, and coo cooking th the po potatoes dr dries th them,” he ex explains. A dry inside is essential, since steam escaping from the inside of the spuds while they roast will stop the crust crisping up properly.

But hang on a minute, what do you mean cooking potatoes in water makes them drier? “Water will always migrate to a greater mass of water,” said Palmer-watts firmly.

For this reason, he says, counterintuitively, it’s better to boil the potatoes than steam them. The water needs to be salted, too – and not just for flavour. “It gives a crisp glassiness to the outside of the roast potato.”

After draining the potatoes, the chef advises, there’s no shaking them in the colander, as they should be falling apart a bit already, but