A day in advance, prepare the shortcrust pastry and ricotta (if you are using the homemade method), and cook the wheat (if you are using the raw wheat).
For the pastry. Blend all the ingredients in a blender for a few seconds, until they form a ball. Please note: both vegan butter and water must be cold from the fridge! Then, wrap the dough in plastic wrap or transfer to an airtight container and store in the refrigerator.
For cooked wheat (skip this step if using precooked wheat and read the notes). Rinse the pearl barley under plenty of running water, then place it in the Instant Pot together with the rest of the ingredients. Select the High Pressure program and set 45 minutes (slow release = do not open the valve at the end of cooking). Alternatively you can cook on the stove with 200 grams of extra soy milk over high heat until boiling, then lower the heat and simmer for 1 hour and 30 minutes without stirring.
Transfer the cooked wheat to a container, allow to cool completely and then place in the fridge until use. If there is any extra liquid, drain the excess before transferring it.
The day after, take half of the cooked wheat and blend it with the vegetable cream to be whipped, until you get a cream with a smooth consistency.
Prepare the ricotta cream by working the vegetable ricotta with the sugar, then add the grated zest of a lemon and an orange. Gently dissolve the tapioca in the dough (you can use a blender for a more homogeneous result).
Incorporate the creamy wheat mix, the cooked wheat and the candied fruit. Then mix everything evenly.
Preheat the oven to 160 ° C (320 ° F).
Roll out the shortcrust pastry to a thickness of about 4 mm, wrap the pastry on the rolling pin and place it on a 26 cm diameter pastiera mold. Cut off the excess dough from the edges and prick the bottom with a fork.
Place the dough in the freezer and, with the remaining scraps, make strips about 3 mm thick and about 1 cm wide, using the pizza wheel.
Take the pastry from the freezer and pour the filling inside, up to about 5-6 mm from the edge.
Place the first 3 strips on the pastiera starting from the center and at a distance of about 4 cm from each other, then complete with the remaining 3 by placing them diagonally to form diamonds.
Bake the vegan pastiera for about 1 hour and 30 minutes. Do the toothpick test (the dough must be compact), then increase the time to another 15-20 minutes if necessary. For the last 5 minutes, increase the temperature to 180 ° C (355 ° F) to caramelize the surface.
Leave the pastiera in the oven, semi-open, for about 30 minutes after the end of cooking, then allow to cool completely down to room temperature.
In order for the flavors to be perfect, wait at least 48 hours before enjoying it. Serve the vegan Neapolitan pastiera with a light dusting of icing sugar.