In a food processor place the flour, sugar and salt and process until combined. You can also do this by mixing with a fork or a dough blending tool.
Add in the butter and process until you get sand-like consistency (which you can also do using a fork, a dough blending tool or using the tips of your fingers).
Slowly add in the cold water and the white vinegar and process (or combine with your hands) until a soft dough forms.
Wrap this dough in plastic kitchen wrap and let it rest in the refrigerator for 30 min.
Preheat the oven to 350°F and, once the dough has rested, take it out of the fridge and roll it out using a rolling pin on a clean and floured surface until it´s about 0.05 inches (5 mm) thick.
Place the rolled out dough on a pie pan previously greased in a way that covers all the inside of it, making some decorations to make the edges pretty if you want to.
Cover this by placing parchment paper or aluminium foil over it and then put something to keep it from rising too much while in the oven and for it to keep its shape. It could be uncooked rice, beans, etc.
Bake at 350°F for 15 minutes, then take the paper and the rice or beans away, and keep baking it on its own for 5 more minutes.
Take it out of the oven and put it aside until needed.
For the filling:
In a big bowl, whisk the sugar, butter, egg yolks and cocoa powder together.
Then, incorporate the flour and the cornstarch.
Lastly, add in the evaporated milk, instant coffee, vanilla extract and salt, and carefully mix until well integrated.
Pour this filling onto the previously baked pie crust and bake it all at 350°F for 45 minutes until the filling is set around the edges but a little jiggly in the center.
Let it cool completely and then refrigerate for at least 2 hours. Serve with some whipped cream.