Place flour, the butter, and salt in the bowl of a food processor fitted with a metal blade. Process just until the mixture resembles coarse crumbs, about 6 seconds.

Add the fizzy water and pulse until the pastry begins to just hold together, about six to eight times. You may need to add more liquid after the first go around, that’s okay. Do not let it form a ball.

Turn the pastry out on to waxed paper or plastic wrap and flatten the dough into a circle. If the dough is excessively sticky, sprinkle it with several tablespoons of flour. Wrap in waxed paper or plastic wrap and refrigerate for at least one hour.