Preheat your oven to 180 degrees celsius (Fan Forced). If using frozen pastry defrost your pastry.
Chop your rhubarb stalks into inch-sized pieces approximately 2cm.
Place the rhubarb, vanilla essence, lemon juice, water, and sugar in a saucepan. Bring to the boil and simmer until tender, This takes approximately 5 minutes.
Roughly line a pie dish with sweet-short pastry.
Fill the lined pie dish with the cooked rhubarb.
Fold the excess pastry around the edges of the dish over the top of the rhubarb filling. If you have any offcuts of pastry tear them into pieces and roughly scatter them over the pie.
Bake at 180 degrees Celsius (fan-forced) for 30-35 minutes until the pastry is cooked and golden brown.
Enjoy your rhubarb pie warm with vanilla ice cream, pouring cream or mascarpone.