1. Combine the flour, sugar and salt together.  Add the oil and blend in using a pastry cutter, electric beaters or a mixer fitted with the paddle attachment, until the flour looks evenly crumbly in texture.
  2. Add the butter and cut in until rough and crumbly but small pieces of butter are still visible.  Stir the water and vinegar (or lemon juice, if using) together and add all at once to the flour mixture, mixing just until the dough comes together.  Shape the dough into 2 logs, wrap and chill until firm, at least an hour.
  3. Preheat the oven to 200 °C and lightly grease a 12-cup muffin tin.  Pull the chilled dough from the fridge 20 minutes before rolling.