For the bottom, put the flour, salt and butter into a large bowl and use your fingers to make a crumbly dough. Add the sugar and the egg and quickly mix to form a ball. Put your dough into the fridge for 20 minutes.
While the dough is resting you can make the rhubarb and the crumble
Put the rhubarb together with the sugar and the orange juice and the vanilla in a large pan and heat until the sugar is dissolved and the mixture is boiling. Turn the heat to low and simmer for about 12 minutes until the rhubarb is cooked
Crumble
For the crumble mix the flour and the butter together in a bowl and make crumbs out of it with your fingers Stir the sugar and the rolled oats through it and mix it wel.
Take the dough out of the fridge and put it in an ovendish with non stick coating or cover with baking paper and press the dough into the bottom until equally divided Make holes in the dough with a fork and put in the oven for 10 to 15 minutes.
Remove from the oven and increase the temperature to 200 C
Pour the compote on top of the bottom. And make a layer of the crumbs on top
Put the dish into the oven for about 20 minutes or until the crumble topping is nice and golden brown