If you don't have a food processor, here's how to make pastry by hand. Make sure your ingredients, equipment and hands are cool before you start.
Step 1: Rub chilled chopped butter into the flour using your fingertips. For a lighter texture, keep palms face-up to lift and aerate the flour.
Step 2: Add iced water. Using a round-bladed knife in a cutting motion, mix until incorporated and the mixture begins to hold together.
Step 3: Bring the dough together. Transfer to a lightly floured surface. Knead until smooth. Don't overwork the pastry or it will toughen.