Boil the potatoes until softened, then strain and dry before mashing vigorously. Add the butter, double cream and mustard. Mix thoroughly and season to taste with salt and pepper.

• 土豆煮软，滤干后用力捣成泥，拌入黄油、浓奶油、芥末粉捣匀，放入适量盐和胡椒。