Add the flour, sugar, vegetable shortening and non-dairy butter into a mixing bowl. Rub the shortening and non-dairy butter into the flour until it resembles breadcrumbs.

Slowly add the water and bring the mixture together until it forms a ball.

Cover the dough with clingfilm and place it in the fridge for a minimum of 2 hours to rest.

Just before the dough has finished resting, pre-heat your oven to 180C/350F/gas mark 4.

When the dough has finished resting take it out of the fridge and roll out on a lightly floured surface.

Carefully line your pie dish with the pastry and press it gently into all of the corners and grooves then gently prick the base all over with a fork.

Lay a piece of baking paper over the pie crust and then fill it with baking beans.

Place the pie crust into the oven and bake for 15 minutes or until it is just turning golden. Remove the baking beans then cook for a further 10 - 15 minutes until crisp, golden and cooked through.

Wash the rhubarb stalks and cut them into strips to fit horizontally across the top of your tart.

Line a baking dish with some baking paper and lay out the rhubarb stalks. Coat them in the caster sugar and cover the dish with baking paper.

Bake for 25-30 minutes and allow to cool completely.

Reserve the syrup for serving.

Place the soy milk into a pan. Split the vanilla pod scrape out the seeds and place the pod and seeds in the pan with the soy milk.

Put the cornflour and sugar into a bowl. Slowly pour some of the vanilla-infused milk to the cornflour and sugar mix, stirring each time to make sure there are no lumps.

When you have a smooth mixture, pour it back into the saucepan and place it on to a medium heat.

In the meantime dissolve the agar agar in a tablespoon of water. As the mixture heats up, add the agar agar and stir to ensure it heats evenly and lumps don't form.

Heat until the mixture begins to bubble then pour into the tart case.

Arrange the rhubarb strips on top of the tart.

Serve the tart with a drizzling of the reserved rhubarb syrup.