Making Shortcrust Pastry

Rub 125 g cold diced butter into 250 g flour and a pinch of salt with your fingertips, until it looks like breadcrumbs with a few pea-sized pieces. Add a beaten egg yolk and two or three tablespoons of ice water and press it together. Don't knead it; stop as soon as it holds. Flatten it into a disc, wrap it and chill it at least an hour. Overworked, warm pastry turns tough and shrinks in the oven. For sweet tart pastry, add 50 g of powdered sugar and use a whole egg.