Prepare the puff pastry dough first. Cube the butter and place it into the freezer for 15 to 20 minutes, until nicely chilled. I recommend using a food processor to break the butter into the flour. Depending on the size of your food processor, the flour and butter may need to be halved. Place half the butter and flour into the food processor and pulse for a minute, until fine crumbs form. Empty the flour and butter mixture into an extra large bowl, then do the same for the remaining butter and flour.
In a large measuring cup or bowl, combine the wet ingredients: eggs, water, vodka, vinegar and salt. Whisk the ingredients together for a few minutes until a smooth mixture forms. Create a well in the dry ingredients, then pour in the wet ingredients. Use a spatula to combine the flour with the water, creating a soft dough. Once the dough starts to come together, switch to mixing with your hands.
Knead the dough very minimally, just until the flour is incorporated and no dry patches remain. Do not over knead the dough. Using a sharp knife or bench scraper, divide the dough evenly into 12 pieces; I like to use a kitchen scale for accuracy. Roll each piece gently into a ball, then place onto a tray. Cover the tray with plastic wrap and place the dough into the refrigerator to chill; about 1 hour in the refrigerator, 30 minutes in the freezer.
After chilling the dough, preheat the oven to 375F. Prepare 2 silicone mats. Work with 2 pieces of dough at a time, keeping the rest chilled. Gently shape each piece into a disk, then use a rolling pin to roll out the dough into an 8-inch circle. Use an 8-inch pan or round of parchment paper to cut the dough evenly; keep the scraps on the pan. Save the baked scarps for garnishing the cake.
Transfer the silicone mat onto a baking sheet and bake the layers for 8 to 10 minutes at 375F, until the pastry is golden brown. Remove the layers from the oven and cool completely on a wire rack. Prepare the remaining layers the same way. I like to use 2 mats so I can prepare the next layers while one pan is baking.
Vanilla Custard Filling:
While the dough is cooling and baking, prepare the vanilla custard. Place the egg yolks and sugar into a large mixing bowl. In a small ramekin, combine the cornstarch and water, creating a slurry. Add the slurry to the egg yolks, then whisk vigorously for 2 to 3 minutes, until the mixture is light and creamy. Pour the milk into a large pot and add the flour, then whisk until smooth.
Cook the milk over medium heat, stirring occasionally, until the milk is steaming but not boiling. Slowly temper the hot milk into the egg yolk mixture - add a cup at a time into the yolks, mixing well after each addition. Once the two mixtures have been combined, pour the custard base into the pot. Cook the custard over medium-low heat, stirring constantly with a rubber spatula, for 8 to 10 minutes, until the custard thickens into a pudding. It should hold its shape on the back of a spoon. If the custard starts to clump, whisk for a minute until smooth.
Once custard is thickened, remove it from heat and add the butter and vanilla. Whisk until the butter is completely melted. Cover the custard with a lid or plastic wrap and cool completely at room temperature.
Assembling the Cake:
To assemble the cake, first allow the layers and the custard to cool completely. First, soak each layer lightly with the sweetened black tea, using a pastry brush. Add 1/4 cup of vanilla custard between each layer, using an offset spatula to spread the custard evenly. Use the remaining custard to frost the top and sides of the cake.
Place the baked pastry scraps into a ziplock bag and crush the pieces with a rolling pin into fine crumbs. Press the crumbs into the sides and top of the cake gently. Allow the cake to set and chill in the refrigerator overnight. When ready to serve, remove it from the refrigerator at least 1 hour prior to allow the layers to soften. If desired, drizzle the cake with melted chocolate and sliced fresh strawberries.