Cut in the butter a little, then add the shortening, work into a paste, to create a crumb, keeping the mixture light.
Whisk together the egg, vinegar, vanilla and water.
Work the mixture to a dough, use an electric mixer, fitted with a paddle attachment if desired, I work it with a spoon, until it isn't wet, then use my hands to moisten the crumbs, with the cohesive dough, at the bottom of the bowl.
Remove the dough, it should not be crumbly, shake it over the bowl, if there are any crumbs left, set the pastry aside, add a few drops of water to the remaining mix, gather together, and add to the whole.
Rub both sides of the dough in flour before putting into a zip top bag, to chill for at least an hour before using the rest of the flour, for rolling and baking the dough.