Photograph: Tara Fisher
Measure the flour and a generous pinch of salt into a large mixing bowl.
Coarsely grate the fat(s) into the flour. Using a palette knife or a round-bladed knife, stir the flour until all of the fat pieces are covered in flour. Add 2-3 tablespoons of ice-cold water, and bring together with a knife.
Turn out on to a lightly floured surface and, using your hands, bring together into a soft dough. Wrap in clingfilm and chill for 30 minutes.
On a lightly floured surface, roll the pastry into a 50cm x 20cm piece. Fold one end of the rectangle into its centre and repeat with the other half to give you a rough square.
Wrap the pastry in clingfilm. Chill for at least 30 minutes before rolling out for your chosen recipe.
If you're making Jo's sausage rolls, use 500g for those and freeze the rest to use later.
Kitchen secret: it's important that you use ice-cold water, so pop a jug in the freezer a few minutes before you need it. To make it easier to grate the butter, keep the wrapping around the side of the butter you are holding, it will help you to grip it and prevent it melting as you grate.