Many cooks cling to a cherished belief that if you slice potatoes before boiling them to make mashed potatoes, they will absorb water and make watery mash. This myth came to mind recently in conversation with a group of colleagues, fellow judges in a “Mash Challenge” organised by the British Potato Council.

The winner, from some 22 entrants, was Barry McGuigan, the boxer, who triumphed in the recent series of Hell’s Kitchen with Marco Pierre White. He won largely on the basis of some killer mashed potatoes made to Mr White’s recipe. McGuigan Mash, made with Desiree potatoes, butter and milk, is ethereally light yet sumptuously buttery.

With judging over, I asked how they cooked the spuds. Mark Clement, head of the catering department at Hammersmith and West London College, said they cut them in chunks before boiling in salted water for 15-20 minutes. The results disproved the myth about water contact.

But it can be done in a greener way. Two greener ways, in fact. Firstly, slice peeled spuds to the thickness of a £1 coin, bring to the boil in plenty of water, simmer for 5 minutes with the lid on, then turn off the heat, and cook through residual heat for 5-10 minutes more. I recently did 660g of King Edwards this way. Cooked and drained, they weighed 670g. So much for the idea of absorbing loads of water.

The second method involves steaming in the pressure cooker. Peel, cut in chunks around an inch thick, bring up to full pressure, and steam for 5 minutes. Turn off the heat and cool till the lid can be removed – 980g of peeled spuds weighed an even kilogram after cooking.

Energy use: cut by at least two thirds. Water absorption: negligible. Mash: delicious. Not as good as Barry McGuigan’s, perhaps – but he had an assist from Marco Pierre White.

greenkitchen@thetimes.co.uk

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