Preheat the oven to 200C/400F/Gas 6.
For the pastry straws, place the pastry onto a baking sheet, prick all over with a fork and bake in the oven for five minutes.
Remove from the oven, brush with beaten egg and sprinkle over the caster sugar. Return to the oven and bake for 6-7 minutes, or until golden-brown.
Remove from the oven, dust with icing sugar and cut into straws or long triangles.
For the rhubarb ketchup, place all the ketchup ingredients into a small pan and cook over a medium heat for 6-8 minutes, or until softened. Pour into a small bowl and leave to cool.
To serve, place the pastry straws onto a plate with the rhubarb ketchup alongside.
