I prefer to make mash at Christmas. If you prefer duck fat roast potatoes, then do them. But you don’t need both
I recommend making your mash the morning of Christmas or even the night before
For many of us the most stressful thing about Christmas is cooking the vegetables. We complicate our day with potatoes three ways, carrots two ways, and Brussels sprouts cooked the one way that makes them decidedly unappealing: boiled until a grey-green.
We would do well to focus on a few vegetables at Christmas, cooking them one way and in a fashion that befits the long time they remained in the ground in order that you may enjoy Christmas. The central issue is of the potato, the unfortunate hallmark of Irish cuisine all around the world (I’m working on changing that). While your unfettered instincts will tell you that you need this tuber at least three ways, hold fast and ignore that inner voice.
I prefer to make mash at Christmas. If you prefer duck fat roast potatoes, then do them. But you don’t need both. To make mash, I use a ratio of 2:1 in terms of potato and butter. That is, for 1 kilo of potatoes, I use 500g of butter. Please, don’t pretend to be shocked or be concerned about the calorie content. You’ll eat enough chocolate over the holidays.
To make the mash, peel and cut the potatoes so that they are all the same size. Bring to the boil and then simmer (I mean simmer, as in do not boil them for 45 minutes). Strain the potatoes. I recommend you use a potato ricer, a moulin or a drum sieve to make your mash; it will be lumpless and lusciously mounted with buttery love. Place the potato in the drum sieve with cold cubed butter and seas salt. Push it through with a plastic dough scraper.
When nearly all the potato has gone through the fine sieve, you’ll notice that some bits remain: these are those horrible little lumpy bits that would have ruined your pomme purée. Whip the lot together with a spatula. Check the seasoning. I recommend making your mash the morning of Christmas or even the night before. There’s no need to stress yourself out, trying to carve a turkey and mash potato at the same time.