In a heavy-based saucepan blend the cornflour in 100ml almond milk. Stir well until well blended.
Add 400ml [UK 14 fl oz / US 1 ¼ cup] almond milk in the saucepan. Add the soya cream, caster sugar, vanilla paste and agar agar flakes. Mix well.
Slowly bring to the boil, stirring constantly with a whisk. Once the mixture starts boiling, cook for 3-4mins whisking constantly. You will see that the mixture starts to thicken. (Do not expect it to thicken as much as when you use eggs. Agar agar solidifies when it cools down).
Leave the mixture to cool down, stirring from time to time.
Now you can prepare the shortcut pastry. Mix the flour and soft dairy-free butter by hand or food processor on pulse setting until you get a mixture that resembles breadcrumbs. Add 1 tbsp caster sugar.
Add almond milk one tbsp at a time until the mixture comes together as a ball. Roll out the pastry and place in a 25cm (9.8 inches) loose bottomed tart tin. Prick the pastry all over with a fork.
Place a sheet of parchment paper inside the pie and fill it with baking beads.
Blind bake the pastry for 15-20mins. Keep an eye on it. It should be golden and crisp but not overcooked.
Once the crème pâtissière has cooled down completely, fill the cooked pastry case with it.
Wash strawberries. Remove stems and cut them in half. Dispose the strawberries on top of the crème pâtissière.
This vegan strawberry tart should be eaten the same day it is assembled. The crème pâtissière can be made in advance.
Just before serving, dust with icing sugar if you wish.