It is important to choose the right potato for mash, to not only give it the fluffy texture but also to give the mash a depth of potato flavour – to fulfil these requirements Desirée or King Edward potatoes are perfect. To serve four people, use a potato peeler to pare off the skins of 2 lb (900 g) potatoes as thinly as possible, then cut the potatoes into even-sized chunks – not too small; if they are large, quarter them, and if they are small, halve them. Put the potato chunks in a steamer fitted over a large pan of boiling water, sprinkle 1 level dessertspoon salt all over them, put a lid on and steam the potatoes until they are absolutely tender – they should take 20-25 minutes. The way to tell whether they are ready is to pierce them with a skewer in the thickest part: they should not be hard in the centre – you need to be careful here, because if they are slightly underdone you do get lumps.
When the potatoes are cooked, remove them from the steamer, drain off the water, return them to the saucepan and cover with a clean tea cloth for about 4 minutes to absorb some of the steam, then add 2 oz (50 g) butter, 4 tablespoons milk and 2 level tablespoons crème fraîche.
Use an electric hand whisk on a slow speed to break the potatoes up. Then increase it to high and whip the potatoes up to a smooth, creamy, fluffy mass. Taste and, if they need it, season.
To make low-fat mashed potatoes, replace the butter, milk and crème fraîche with 5 oz (150 g) of Quark (skimmed-milk soft cheese) and 2-3 tablespoons of semi-skimmed milk.