To get your purée right...
Choose a floury variety of potato such as Bintje or Mona Lisa. These are the same potatoes you’d put in your soups, or use for chips and gnocchi. It’s essential for a successful purée. If you go for a waxy variety like Charlotte, your potato is liable to turn gluey.
You can use milk, or half milk and half cooking water, or just the cooking water. That’s down to your taste and to whatever you’re serving it with. If the rest of the meal is already rich, keep the purée light.
You can add a small knob of butter or a huge amount. Some restaurant chefs have a heavy hand: Joël Robuchon recommended 250 g of butter and 25 cl of milk for a kilo of potatoes.
