Sift the flour, salt and baking soda into a large bowl. Rub the butter into the flour with the fingertips until it has the consistency of a coarse meal. Make a well in the centre. Mix the egg with the water and pour gradually into the flour, mixing with a wooden spoon until the dough is smooth. Gather the dough into a ball, wrap in waxed paper and refrigerate for 1 hour.
Heat the oil or